Airgun Accuracy

Only accurate airguns are interesting!

Walther LG 400 for Field Target

I am starting the conversion of a Walther LG 400 air rifle from 7,5 Joule to a 16 Joule / 12 footpound field target rifle ( Field Target shooting ). I like the LG400 for its improved mechanics and for its better handling compared to other rifles. But Walther does not make an 16 joule version of the LG 400. So I’m going to do my own conversion. I am currently shooting an Walther LG300 that I converted to 16J myself (link here).

I used the Konfigurator at the Walther website and ordered an Walther LG400 from Sportwaffen Hasselhorst in Germany. I chose the basic Economy version and added the 3-D pistolgrip adjustment, the height and cant adjustable forestock and chose blue laminate woodwork instead of the black Protouch woodwork. See the picture.

Walther LG400 Blue Laminate Woodwork

Walther LG400 Blue Laminate Woodwork

Walther LG400 Pro-touch

Walther LG400 with black Pro-touch woodwork

So why did I choose the Walther LG 400?

I currently shoot a Walther LG 300 for field target and like this rifle a lot. It’s accurate, easy to service, has a solid build,  has a good overall weight balance and the aluminum stock can be adjusted to my liking. It was about 20 years ago when I first held a Walther LG 300 Alutec for 10 meter ISSF shooting and the moment I brought it to my shoulder I knew this rifle fit me like no other.

The LG 400 is the successor to the LG 300. Compared to the LG300 the LG400 has some interesting improvements:

A new aluminum stock with:

  • Height adjustable fore end which can be raised and move longitudinally in a rail (the LG300 was only adjustable for cant)
  • A system/breechblock to stock connection with 1 bolt from the bottom (LG300 has 2 side bolts and 1 bottom bolt, this could cause bad accuracy and impact shifting depending on bolt torque and ambient temperature changes)
  • More space for adding weights (LG300 only in the fore-stock, LG400 also in the rear stock)
  • Pistolgrip on a ball joint that can be adjusted in all directions (LG300 in 2)
  • Cheekpiece can be moved in the longitudinal direction
  • The rear stock can be offset from the center line of the rifle
  • The bolts used on the LG400 stock are from stainless steel. A nice feature on a field target rifle that is going to be used outdoors in a wet country like The Netherlands. On my LG300 I used to oil the bolts regularly with BreakFree CLP to protect them from rust.

And the LG400 has a new system / breechblock that has compared to the LG300:

  • Magnetic shot reaction absorbing system (LG300 has a spring operated system, the LG300 XT has a pneumatic system and newer LG300XT systems (Pro-touch/Carbontec ) have the new magnetic system as well, see on this page: Walther shot reaction Absorber and Equalizer systems)
  • Lighter lighter hammer (14 gram vs. 28 gram) and lighter hammer spring for minimal shot impulse reaction, shorter lock time and less air consumption


LG400 and 300 hammers

-Lighter valve. The LG400 has a 0,75 gram valve compared to 2,2 gram for the LG300

-A shorter air path behind the firing valve which decreases air consumption

  • The loading/cocking lever has more clearance from the scope/sight rail. This makes it easier to mount a scope. It can also change over from an upward movement to an downward movement. And from right hand side to left hand side
  • A load indicator that shows if there is a pellet loaded in the barrel. Very handy: At least once every time I shoot I find myself  trying to take an almost impossible peek into the loading gate of the LG300 to see whether or not I had already loaded a pellet.

The conversion from 7,5 to 16 Joule

Sighter from the forum has done a 16 joule conversion and this inspired me to do my own. Sighter (or Gert) used a 16J MK2 regulator from the Walther LG300. There are some others that have done conversions as well. Spurlos69 from the Ukraine has made a whole new regulator himself. Aron Jalakas from Estonia uses an Lg400 for FT and his rifle has a 16J LG300 MK2 reg as well. Mick Tromans in the UK has done a LG400 conversion for Jason Goldsmith from the forum.

My own experience before starting the LG400 field target rifle project is based on the conversion of 2 Walther LG300 rifles and a Walther LG200 rifle (see the LG300 page on this website for more info). During these projects I found that the LG300 7,5J MK2 regulator can be adjusted to 95 bar output pressure and the rifle will deliver 16 J. No further changes or expensive parts needed besides adjusting the hammerspring preload. This makes the LG300 the easiest and cheapest 10 meter competition rifle to convert to a Field Target rifle. Anschutz and Feinwerkbau rifles need much more parts and work to make a good shooting Field Target rifle.

The reason for the easy conversion is that the LG300 MK2 regulator has a large enough secondary/output pressure chamber to deliver enough air to propel a 0,543 gram pellet to over 240 m/s. The older LG300 MK1 regulator has a much smaller chamber and cannot deliver enough air.

Looking at the exploded view of the Walther LG400 regulator it is clear that the LG400 regulator has an air chamber that is smaller than the LG300 MK2 reg but larger than the MK1 regulator.

Walther LG400 breech exploded vieuw

Walther LG400 regulator and breechblock

LG300 MK1 regulator and breechblock

LG300 MK1 regulator and breechblock

LG300 XT (MK2) regulator and breechblock

LG300 XT (MK2) regulator and breechblock

The pictures show the difference in size of the secondary or output pressure chamber of the LG400, LG300 MK1 and LG300 MK2 regulators. All these pictures are from the 7,5J versions. Walther also produces a 16J version of the MK2 regulator which has a 10 millimeter longer pressure chamber compared to the 7,5J MK2 reg. The MK2 7,5 J reg has a total length of 75mm while the MK2 16 J reg is 85 mm.

Studying these pictures for the size of the air chamber it looked to me that it might be possible to use the original LG400 reg to get 16J. Because it is bigger than the chamber in the old MK1 reg. The air path from air chamber to the barrel is also shorter on the LG400. This makes the airflow more efficient and therefore increases the chance that the original LG400 reg might be used for the 16 Joule rifle. Using the original LG400 pressure regulator has the advantage of using the newest state of technology that Walther has put into it and and it saves 170 Euro from buying a new regulator. [edit 2015; New info shows that the LG400 pressure regulator is not that much different from the LG300 MK2 regulators. See this page about the Walther pressure regulators (Druckminderer) for more information:  ]

I found an (unconfirmed) post on the Polish forum from Wiecho who said that the 7,5 Joule MK2 reg has a chamber volume of 4,6 cm3 and the MK2 16 Joule field target reg has 8,75cm3. This thread also mentions the size and number of the Belville spring discs inside the regulator according to Bonzoo. The old MK1 type has 24 pcs of 12,5 x 6,2 x 0,7 in an arrangement that looks like  ((())) ((())) ((())) ((())). The new LG300 MK2 16 Joule field target type has 14 pieces of the 10,0 x 5,2 x 0,5 disc springs in the arrangement (()) (()) (()) ((      [put the 2 concave discs “((” on the plunger / piston first].

If the conversion does not work with the original Walther LG400 regulator I can always use the Walther LG300 regulator to get 16 joule out of the LG400 like Sighter and Jalakas have done.

The Walther LG 400 has arrived

I received the Walther LG 400 from Sportwaffen Hasselhorst ( ) in Germany yesterday. The communication with Sportwaffen Hasselhorst was quick and easy and the prices there are most reasonable. It took only 11 days from payment untill delivery of this specially configured rifle.

One of the first things I did after unpacking was shooting the rifle over the chronograph (Combro CB625). I first cleaned the barrel with the pull through delivered with the rifle. This showed the rifle had been shot before because some lead was visible on the patch. This was probably from the test shooting at the Walther factory.

The rifle was delivered with a test shot card. This card shows the accuracy of an 5 shot group at 10 meters distance. The group is so small that it could easily have been just one shot. But as this was shot at 10 meters it will not be a good indicator of the 50 meter performance that is needed for field target shooting.

After cleaning it took the barrel 4 shots to settle again. During these first 4 shots after cleaning the velocity was 2 meter/second lower than the average over the next 20 shots.

These are the results of this rifle in its new and original 7,5 Joule setup with JSB Exact 0,54 gram / 8,3 grain pellets. The first shots after cleaning are not shown.

First Chrono results

Shot  Velocity (m/s)
1    167.5
2    169.5
3    168.4
4    169.1
5    167.1
6    169.2
7    169.2
8    168.5
9    168.3
10  168.3
11   169.1
12   168.4
13   168.8
14   168.2
15   168.2
16   167.9
17   168.4
18   169.5
19   169.2
20   169.0
Average: 168.6 m/s
Extreme spread:  2.4 m/s

[Remark: These are results with my Combro chronograph that later showed to give velocities that are 4,3 m/s too low. The actual average velocity of the LG400 at factory setting will be 172,9 m/s]

The velocity difference of 2,4 m/s (= 7,9 feet per second) over 20 shots with unsorted pellets is very good. I have tested other rifles like the Steyr LG 110, Walther LG 300, Walther LG Dominator and the Airarms EV2 with the same chronograph and pellet type and have never found a lower velocity spread. This may be an effect of the lower velocity of the LG400 because the other rifles were shooting at 16 Joule or around 240 m/s. When the  LG400 is converted to 16 Joule I will test again and see whether it can hold hold this low extreme spread.

The promise is that the measured velocity spread may even be reduced in the future. After some running in time the moving parts of the rifle wear in onto each other and make the LG400 run even smoother .

For now this a nice result and starting point for the field target conversion to 16 Joule.

 Removing and comparing the LG400 pressure regulator

I took some pictures of the removal of the pressure regulator. It is held with two M5 bolts and easy to remove with a 4mm Allen key.


The regulator is off the breechblock now. You can see it is factory set at 72 bar and the manufacturing date is 14th of November 2013.


Here you see the breechblock with green regulator o-ring seal and the valve


LG400 regulator with valve spring and valve


Three Walther regulators and two valve types. From top to bottom: MK1 LG300 Dominator 16Joule regulator with original valve, MK1 LG300 7,5 Joule regulator and the 7,5 Joule LG400 regulator.

Notice the longer regulator extension on the Walther LG400 reg and the much lighter and smaller valve on the LG400. The small bushing holds the valvespring inside the regulator. The longer extension on the LG400 regulator prevents the straight forward swap of the LG300 regulator into an LG400 breechblock. A small adaptor needs to be made to overcome the difference in length.

The output pressure on LG400 regulator is easier to adjust than on the LG300 regulator. On the LG400 reg the adjustment and locking screws can be reached from the outside. You can see the adjustment screw in the first picture of the reg above . The LG300 regulator needs to be taken apart in it’s two halve before you can reach the set and locking screws (see picture below). And these two halves are screwed TIGHT. In my page about the LG300 conversion you can read more about the adjustment of the LG300 regulator

Walther LG300 regulator pressure adjustment screws

LG300 regulator opened in two halves showing the pressure adjustment screws

The conversion part 2: 16 joule with the original LG400 regulator!

I have been busy adjusting the LG400 regulator pressure and hammerspring preload. And the results are very promising. In the end I managed to get 239 m/s  (785 fps)  with the 0,543 gram (8.4 grain) JSB Exact pellet. This calculates to 15.5 Joule. A nice figure on the safe side of the allowed energy level for Field Target competitions.

The first thing I did was mounting the LG400 reg in its original setting to the newly made regulator tester. This showed a pressure of 78 bar. The writing on the reg said it was factory set to 72 bar. I do not trust the old 300 bar manometer I used for this reg tester to much for accurate readings. I checked the new LG400 reg tester with a LG300 MK1 reg that was set to 75 bar on my other LG300 reg tester which has a new 160 bar manometer. This test also indicated that the 300 bar manometer reads 6 bar to high.

Regulator tester for LG300 regulators with 160 bar manometer.

LG400 regulator tester with valve

LG400 regulator tester with valve


LG400 regulator tester opposite side. (The nuts are to keep the bolts in place during storage)

With the new reg tester now calibrated I continued with the adjustment of the Walther LG400 regulator. I unscrewed the locking screw a few turns en gave the pressure adjustment screw half a turn clockwise. This gave a 129 bar output pressure! Way to much for what I thought I needed. So I turned the screw back a quarter turn and the manometer showed 93 bar (corrected value). This is very close to the pressure I use in my LG300 reg. I went on to test this setting on the rifle to see how fast the pellets would be travelling: 170 m/s.

Increasing the hammerspring preload in steps of a quarter turn clockwise resulted in a max velocity of 221 m/s or 13,8 Joule after 1 full turn. More than this one turn did not result in higher velocities The adjustment screw of the hammerspring is at the rear of the breechblock and locked with some red paint.

LG400 breechblock rearside

LG400 breechblock rearside

I was not satisfied with 13,8 Joule so I mounted the reg tester again and set the reg pressure to 106 bar. After some hammerspring adjustments this gave max 229 m/s and 14,8 Joule. Still a bit on the low side of 16 Joule. So I mounted the reg to the tester again and set the pressure to 112 bar. This resulted in 234 m/s. After two 1/8 turns on the hammerspring I arrived at max 239,5 m/s. There was a marginal effect of the last 1/8 turn.

I returned the hammerspring preload to a total of 1 and 1/8th of a turn from the factory 7,5 Joule setting. Overstressing the hammerspring is not what I am looking for. The velocity stayed around 239 m/s (784 fps) and 15,5 Joule.  My goal is reached!

239 m/s (784 fps) is on the safe side but close enough to 16 Joule (12fpe). This velocity is high enough to have no ill-effect on the wind bucking capabilities of the pellet that may result from a much lower velocity.

Chrono results during the LG400 adjustments

Chrono results during the LG400 adjustments

The above chart shows the chrono results during the adjustments on regulator pressure and hammerspring preload adjustment.

I tested some more to check if the velocity stayed constant. I used two chronographs at the same time. My old trusty Combro CB625 on the end of the barrel and the CED M2 from a friend (Thank you, Ronald) in front of that. I wanted to check the values my Combro gives because because I had the suspicion that it gave low velocities.

LG400 Chrono results; Combro and CED compared

LG400 Chrono results; Combro and CED compared

The Combro actually reads too low. 4,3 m/s too low to be exact. This confirmed my suspicion. My LG300 rifle tested high in a match last year over on RCBS chrony and did the same over this CED M2 before . Other shooters at these matches comfirmed that the RCBS and CED gave velocity reading that compared very well to their own findings.

But more important: This Walther LG400 rifle is stunningly constant at 16 Joule. The CED chrony showed an extreme spread of only 0,7 m/s (2,3 fps) over ten shots. The Combro showed a 1,2 m/s (3,9 fps) extreme spread. All this with unsorted, unlubed pellets straight from the JSB tin!

But I am not ready yet. What needs to be tested next is the shot count that this setup can deliver from a 200 bar cylinder fill, the temperature stability and of course the ACCURACY!

More info to come when I find the time to shoot it at 50 meters with some batches of pellets.

 Making more Height

When ordering the LG400 I chose the adjustable ‘Expert’ type of forestock raiser over the standard one that is only stepwise adjustable with bushings.

LG400 'Expert' adjustable type of forestock raiser

Walther LG400 ‘Expert’ adjustable type of forestock raiser

Hamster with new 50mm pivot links (the two short links are shown for comparison)

Hamster with new 50mm pivot links (the two short links are shown for comparison)

This LG400 Expert hamster (or forestock raiser) drops a maximum of 90 millimeter (3,5 inch) below the centerline of the barrel. This may be enough for ISSF style 10 meter standing position shooting but for field target it is not enough. Especially when shooting with the rifle rested  on the knee. My Walther Lg300 has the hamster set to a drop of 130mm (5,1″) below the barrel. The construction of the adjustable hamster works with two pivot links. These are originally 10mm long. To get more height adjustment I made two new 50mm long pivot links from some 10mm square aluminum bar. The new links work as good as the old ones. They are 2,5mm thicker than the original ones to give some additional strength

I can now set the hamster to the desired height and copy the stock adjustment settings from my LG300.  This will make it easier to set up the new rifle to my shooting position.

Scope Mounting

I mounted the scope, a fixed magnification Leupold Competition 40×45. I had already made a scope raiser for my Walther LG300 from an Airforce/Gunpower scope rail. These scope rails are strong, have enough length for comfortable scope placement, are easy to order and are not expensive (around 17 euro). The main reason to use this scope rail is the short length of the front 11mm dovetail on the breechblock. This limits the positioning of the scope further forward. To establish a good eye relief the front scope mount needs to be further forward than the front dovetail on the breechblock allows.

Scope mounted on the Airforce/Gunpower scope rail

Scope mounted on the Airforce/Gunpower scope rail

To make the Airforce rail to fit the Walther LG300 and LG400 rifles they need some machining. When loading the rifle the 2 pivot links that connect the cocking lever to the hammer and to the loading bolt move above the 11mm dovetail of the breechblock. For normal scope rings this is no problem but the Airforce rail is wider than the breech block and some material from the side of the rail and one of the bolt heads need to be removed. You can see this in the picture.

I also milled a gap in the scope rail over the loading port for easier access and loading of the pellet. To keep the rail as strong as possible I milled the gap over the loading port under a 45 degree angle to keep as much material as possible on the left hand side. I plan to remove the original black finish from the rail to get an aluminum color. This will match the colors of the LG400 better.

The scope is mounted in Sportsmatch ATP61 height adjustable scope rings. When correctly set up these allow the scope to work in the middle of its elevation adjustment range. This allows for enough click adjustment up and down for all shooting distances from 7 to 50 meters. It also makes sure the scope is working in its optical center were the image has the best quality because you are looking through the center part of the scopes lenses.

To set the scope mounts I first adjust the elevation knob of the scope to the center of its adjustment range.  Then I start shooting at a paper target at 50 meters and adjust the rear scope mount upward until the point of aim and the point of impact are almost the same in the vertical plane. I then lock the rear and front scope mounts. I make the final small correction with the elevation knob to get the 50 meter click value and finally adjust for windage.

John Costello using the Airforce/Gunpower scope rail on his Steyr rifle

2013 Field Target World Champion John Costello using the Airforce/Gunpower scope rail on his Steyr rifle

The Airforce scope rails are really good value for money. They fit very well on the 11mm dovetail of the rifle. They are straight, which is shown by the little amount of windage adjustment that is needed when setting up the scope. The 2013 field target World Champion John Costello uses one on his Steyr field target rifle as well.

The First Accuracy Results (29-04-2014)

IMAG1591Let me start with saying that the results of last evening were not what I would like to see for accuracy.

Because this was the first time I was shooting the LG400 at targets I needed to zero the scope first. I put a paper target at 23 meters and the first pellet landed in the 5 ring at 5 o’clock. I shot some more and adjusted the scope until the pellets landed at the point of aim.

Then I put a paper target at 52 meters distance and did a total of 60 shots from three different batches of JSB Exact 8,4 grainers. I shot in the sitting field target position with pellets straight from the tin. With my Walther LG300 and LG200 rifle I normally shoot 16 to 20mm groups this way when the wind behaves itself. Which it did this evening.

The best 5 shot group measured 24 millimeter outside to outside (0,95 inch). It is the group you see on the right hand side target middle row. The ten ring measures 10mm to give you a reference.

I chronoed the first 15 shots and velocity was between 239,7 and 241,0 m/s. That is a spread of 1,3 m/s or 4,3 feet per second. So the velocity spread is still very good and has not changed from the first chrono testing.

This result means some more tinkering is needed on the LG400. Maybe the current regulator output pressure of 112 Bar is too high for these pellets and they get deformed by the high pressure to the extent that accuracy suffers.

I think that the next step will be to try the LG300 MK2 7,5J regulator which is set at 95 bar. This is the quickest way to see if accuracy improves at a lower pressure setting. I could also try to make an extension block for the LG400 regulator to get more air volume. I could then lower the reg output pressure on the LG400 regulator. But this is much more work than making an small adapter to fit an LG300 regulator to the LG400.

Difficulties Loading a Pellet?

On the Shooting-the-Breeze forum somebody commented that the loading a pellet in the Walther LG400 was troublesome. According to him the 8.4 grain JSB’s could sit ‘side on’ in the loading trough. If this would happen and the loading probe is closed it could result in damaged or stuck pellets.

I have now shot the LG400 for over 100 shots and I can say that all those JSB Exact 8,4 grain pellets loaded without any problem. I even find loading a bit easier than with my LG300. The loading trough seems a small bit deeper on the LG400 so the pellets drop in easier.

There is absolutely no way the pellet can sit ‘side on’ in the loading trough. The loading trough is just not wide enough for that. It is 5.75 mm wide only a tiny bit wider than the 4.50 mm pellet. So there is no need for additional work like sleeving the pellet trough which was suggested. Maybe the older (from more than 2 years ago) LG400 that was the subject in this post had a different loading trough than current production models? Walther just might have taken this criticism to heart and changed the loading trough and pellet probe?

Pellet in LG400 loading trough

Pellet in LG400 loading trough

So I must disagree with the comment that the LG400 has difficulties in loading the pellets and needs a lot of additional work to overcome this problem.

Fitting the LG300 MK2 7,5 Joule Regulator to the LG400

I made a small adapter on the lathe to be able to fit the Walther LG300 type regulators to the LG400 rifle.  The LG300 regulator has a shorter protrusion than the LG400 reg has.

Turning the adapter on the Myford ML10 lathe

Turning the adapter on the Myford ML10 lathe

I took some 15mm diameter aluminum rod and made a small 4.25mm long and 12.75mm outside diameter aluminum adapter that fits into the LG400 breechblock. On the regulator side I reduced the diameter to 9.25mm to fit an 9.25mm ID x 1.78mm o-ring. This o-ring seals the regulator side. On the breechblock side it seals on the original seal.

Adapter with o-ring on

Adapter with o-ring on

LG300 reg and adapter reg side

LG300 reg and adapter reg side

Lg300 reg and adapter

Lg300 reg and adapter block side

Adapter with o-ring in the LG400 breechblock

Adapter in the LG400 breechblock

I put the LG300 regulator (set at 95 Bar output pressure) in place and shot the rifle over the chronograph. The hammer spring preload was still at the setting for the 112 Bar LG400 reg and the first shot with the LG300 regulator produced 253 m/s. I reduced the spring preload stepwise to get to 239 m/s. This took a bit more than one full turn on the set screw.

I chronoed for 10 more shots and to my relief the very small extreme spread in velocity that I had seen with the LG400 reg on had remained the same. I got a lowest velocity of 238,1 and highest of 239,5. This shows that the very constant velocity that the LG400 produces is not caused by the new type LG400 pressure regulator but by the rest of the mechanics (valve, valve seal, hammer) in the breechblock.

I refilled the air cylinder to 200 Bar and let it sit overnight to check for possible leaks from the new adapter. The next morning the manometer on the cylinder still showed exactly the same pressure meaning the adapter seals well.

Next thing is to check for accuracy at 50 meters with the new reg in place. This will have to wait for next week Tuesday evening at the club.

Some more testing

(May 6th 2014)

The weather was nice for some testing at 50 meters/55 yards last night to see if the MK2 regulator would improve the results.
And yes it did. The best group now was 16 millimeter / 0,63 inch outside to outside. Followed by quite some 20mm / 0,79″ groups. Al shot from the sitting field target position and pellets straight from the tin. The 8,3 grain JSB Exact with die number 80 gave the best results just like in my LG300.

Eight five shot groups from the LG400. Ruler is in centimeters

Eight five shot groups from the LG400. Ruler is in centimeters

During this session I removed the 2 screws from the front barrel holder which improved the results somewhat. It helped to get rid of the low flyers you see in the right hand column of the target. At first the top half of the barrel holder lightly pushed the barrel down. I had already noticed this when assembling the rifle and had emailed the Walther factory about the correct adjustment of the system in the stock.

At the rear of the breechblock there is a horizontal slit in which a round disc that sits on a screw in the stock can be adjusted up and down. In German it is called the “Stutzspindel”  or Support spindle. Using the screw you can adjust the rear of the breechblock up and down. This causes the barrel to go down or up as well.

The support spindle screw

The support spindle screw

Walther reacted promptly and according to them the correct adjustment of the rear support is as follows:

1. Mount the breechblock in the stock by securing the center stock screw (the one that sits under the regulator).

2.Then adjust the support screw inwards (clockwise) until it very lightly touches the breechblock.

3. Then tighten the two screws from the front barrel holder.

Having done this I noticed that the two screws of the barrel holder would not go in their threaded holes unless I pushed the barrel down lightly. The barrel holder is designed to allow a free floating barrel. The holes in the stock are large enough to give a lot of play to the top half of the barrel holder. There is a thin plastic ring (it looks like the plastic rings that sit  inside the bonded washers that are used to seal pneumatic fittings) around the barrel under the barrel holder that lightly contacts the barrel holder. So it is probably better to speak about a semi-free floating barrel

LG400 Barrel Holder

LG400 Barrel Holder

But in my case I needed to push the barrel down a bit to get the 2 screws in. Meaning the barrel is not completely free floating. During the shooting session I removed the 2 screws completely and the low flyers disappeared.

A 16mm group is quite good but I am not completely satisfied with the accuracy result yet because it is not consistent enough to my liking. Too many 20mm or larger groups. There is of course some shooter error in the above groups but I found it easier to get consistently small groups with the LG300. Next time I will try to shoot the LG400 and LG300 side by side to see the difference in accuracy in the same shooting session. Or I will try to shoot the LG400 from a benchrest to try to eliminate the shooter error. This will show whether the LG400 has the accuracy but that maybe the stock adjustments or weight distribution are making it difficult to shoot consistent small groups.

The 16 Joule Walther LG300  regulator.

Tuesday 20th of May

The LG300 MK2 regulators. 16J left, 7,5J right. Notice the difference in lenght.

The LG300 MK2 regulators. Top: 16J, 7,5J below. Notice the difference in length.

Yesterday I installed the 16 Joule MK2 LG300 regulator on the LG400. This regulator has a larger pressure chamber of 8.75 cm2 compared to 4.6 cm2 for the 7,5 J MK2 reg. On the reg tester it showed 80 bar output pressure. This resulted in 236 m/s (774 fps) with the same hammerspring setting that gave 239 m/s (784 fps) with the 7,5J reg set at 95 bar (8.4 grain JSB). Increasing the hammerspring pre-tension half a turn resulted in only 1 m/s extra. This is a very small response compared to previous adjustments on the reg at 95 bar. I guess the 8.75 cm2 of air at a pressure of 80 bar is only just sufficient to reach this velocity.

I returned the hammer spring preload back to the first setting. The LG400 is now going 15 joule (236 m/s / 774 fps with 8.4 grain JSB). I will test this setup for accuracy tonight. Let’s hope the weather is okay with little wind to allow for some good shooting weather.

 The Walther LG400 Shoots Very Accuracte Now

21th of may 2014

Last evening the weather was favorable for some good testing. 22 degrees Celcius and most of the time there was no wind at all. I put 200 bar in the cilinder and started shooting from the sitting FT position at a paper target placed at 50 meters / 55 yards. I had 3 different tins of 8,4 grain JSB Exact.

-4,52 head size with die no. 80

-4,52 head size with die no. 11

-4,51 head size with die no. 21

(For explanation of die numbers see:  JSB labeling numbers explained)

I started with the no. 80 because that shoots very well in my LG300. And after 3 groups of 10 shots I thought I had lost my shooting abilities or something was seriously wrong with the LG400.

First 3 groups of 10 shot@50meters. 4,52 Die 80.

First 3 groups of 10 shot@50meters. 4,52 Die 80.

We then had a cease fire and I went over and put up a new target.  The home made benchrest table from Kees became available so I took a sandbag and set myself at the table with the front of the rifle supported with the sandbag and the rear with my left hand. I took the 4,51 die no.21 and shot 3 groups of 10 shot. This pellet took some 10 shots to settle and then the grouping became ever better with an occasional flyer. Smallest 10 shot group with no.21 was 14 mm (outside) with 2 flyers.

I then went to 4,52 die no.11. This pellet also took some 10 shots to settle itself in the barrel and started shooting decent groups around 22mm. I then went back to 4,52 die no. 80 to check if this pellet really was not performing in the LG400 when shot benchrested. No problem: 34mm. I tried another 10 shot and this shot 30mm.

This 4,52 pellet is really not performing in the LG400 where it was shooting 16mm groups in the LG300.

This also confirms again that the head size on the JSB tins is not a good indication of the accuracy of the pellet – rifle combination. You really need to test batch numbers and cannot trust that a head size 4,52 pellet is always doing well in your rifle.

10 shot groups from die 21, 11 and 80.

10 shot groups from die 21, 11 and 80.

Another bad 10 shot group from die no.80

The other 30mm 10 shot group from die no.80

I continued shooting with head size 4,52 die no.11. This now shot the best group of the evening. An one hole group of 14mm (outside to outside). One flyer made it 18mm for the ten shots in total.

18mm 10-shot group with die no.11. 14mm when flyer excluded.

18mm 10-shot group with die no.11. 14mm when flyer excluded.

The Walther LG400 field target conversion Summary:

I installed the Walther LG300 MK2 16 Joule regulator ( Walther part number 2693038 ) and it was set at 80 bar output pressure. To install this LG300 regulator on the LG400 rifle you need a special adapter (see above).

Velocity was 236 m/s (774 fps) with 8,4 grain JSB. This setup was tested for accuracy at 50 meters/55yards with 3 different die numbers and two head sizes of JSB Exact 8,4 grain pellets. (For explanation of die numbers see:  JSB labeling numbers explained)

Head size 4,52 die no.80 shot poor 30mm to 34mm 10-shot groups.

Head size 4,51  die no.21 shot a 14mm 10-shot group with 2 flyers which made it 23mm.

Head size 4,52 die no.11. shot a 14mm 10-shot group with one flyer which made the total 10-shot group 18mm.

When changing from one die number to the other it took at least 10 shots for the new pellet to settle in before the new die number started shooting smaller  groups.

The air consumption was low. I used the 200 cm3 steel cilinder filled to 200 Bar. After unscrewing it from the scuba bottle and cooling down the manometer showed a little less, I’d say 195, it’s hard to read small differences on the cilinder manometer.  After 90 shots it was on 100 Bar. The 16 Joule MK2 reg is set at 80 Bar so theoretically there would have been some more shots. But I switched to another cilinder with 200 bar by then. With the same cilinder and fill on the LG300 I got 70 shots.

With 90 shots from an 200cc 200 Bar fill the LG400 shows its claimed air economy at 16 Joule.

The conclusion is that the Walther LG400 field target rifle is now shooting good groups at 50 meters with 2 different batches of pellets.

Next thing is to test for consistency under different temperature and weather conditions. I think I’ll put the LG400 in the freezer next time I shoot it. For the results of the freezer test see this post:

Second place in the 1st FT match with the Walther LG 400

14th of June 2014

Last Saturday I shot the LG400 in its first Field Target match.  It was a 50 shot match for the Dutch National Championships at FT Schalkhaar. I shot a score of 41 out of 50 ( This score tied for the first and second places and in the shoot-off  I missed the kneeling shot at a 25mm target at 33meter and came second.

41 seems to be my number this year. I shot 3 FT matches (FT Schalkhaar 12th April, Helmond 18th May, FTSchalkhaar 14th June) until now and in all of them I shot 41 points 🙂 The first two matches with the Walther LG300 and the last one with the LG400.

The course was said to be quite difficult by many shooters (4 standing targets and 4 kneelers). The wind with was blowing with speeds up to 27 km/h (17 mph) and was changing in force and sometimes suddenly changed 90 degrees in direction.

Shooting the LG400 for the 1st FT Match on the 14th of June 2014

Shooting the LG400 for the 1st FT Match on the 14th of June 2014

The LG400 shot flawless. It feels like the shot reaction is somewhat less compared to my LG300 with the older type spring loaded Absorber. Loading a pellet is just a bit easier compared to the LG300 and the load indicator is a nice feature for me.  I use a 200cc steel air cilinder instead of the aluminum LG400 cilinder to get some more weight up front. There is space for 3 weights in the stock under the air cilinder. But I had the steel LG300 cilinder lying around and it was much quicker to use this than to make weights to fit the stock. With this setup the weight balance of the LG400 suits me fine. I need to try the adjustment of the pistol grip yet.  For now I just copied the settings from my LG300. The LG400 pistol grip offers much more possibilities for adjustment that I have not yet tried.

I put the barrel holder back in place after milling the barrel hole 2mm larger and milling the holes where the bolts go through to a slot shape to give enough play there. All this to get the barrel free floating. Previously I had the barrel holder removed for testing and this showed better accuracy with a free floating barrel. But the barrel holder protects the barrel for damage when knocking the barrel against something and the rifle just looks better with the holder in place.

10 shots at 50 meters during an Field  Target training session

2nd of July 2014

The weather was nice and the wind was low but present during my training session yesterday evening at FT Schalkhaar. We had setup 12 FT targets between 7 and 48 meters and some paper targets in between at 25, 35 and 50 meters. The picture of the 50 meter paper target is posted to show you some current results from the LG400 at 16 Joule / 12 fpe. The size of the 5 eurocent coin is  21 millimeter / 0.83 inch.

Walther LG400; 10 shots at 50m, FT pos. 1st July 2014

Walther LG400; 10 shots at 50m, FT pos. 1st July 2014

I shot this from the sitting FT position and there is some shooter error in this group.  There also was a little on and off wind from the right but not very much.

The Walther LG400 in action again

I shot the field target match at FT Schalkhaar on the 30th of August with the LG400. Because I was also organizing the match I had no time to use the practice range before the match. This left me with no info on the effect of the wind that day. And I missed a lot of the long shots. Poor excuse I know but I still got 40 out of 50 points and ended at a shared 7th place out of 11 shooters. The winner was Adam Benke from Germany and he scored 46 points. We had competitors from Belgium (Guido and Patrick) and Germany (Adam, Frank and Andreas) visiting our match. It was a very nice match and worth every penny for the work we put in it. The atmosphere between the shooters was very good.  For the full results of the match see here at the website of FT Schalkhaar. Pictures courtesy of Rene404.

August 30, 2014. LG400 in action at FT Schalkhaar.Pictures courtesy of Rene404.

August 30, 2014. LG400 in action at FT Schalkhaar

August 30, 2014. LG400 in action at FT Schalkhaar. Pictures courtesy of Rene404.

August 30, 2014. LG400 in action at FT Schalkhaar

Walther LG400 Exploded view

Walther LG400 Exploded view

Walther LG400 parts list page 1

Walther LG400 parts list page 1

Walther LG400 parts list page 3

Walther LG400 parts list page 3

 Adjusting the Walther LG400 regulator to 112 Bar

At a request (see comment of 2014/10/07 below) I have determined how much the setscrew on the LG400 regulator needs to be turned to adjust the output pressure from the standard 72 Bar setting to the 112 Bar setting for 16 Joule / 12 FPE. For people who want to use the original LG400 regulator and do not have a regulator tester this may indicate a starting point for setting their regulator. Keep in mind that every single regulator may have its own characteristics and may respond differently to adjustments.

LG400 reg set at 72 bar output pressure

LG400 reg set at 72 bar output pressure

LG400 reg set at 112 bar output pressure

LG400 reg set at 112 bar output pressure

The measured rotation to go from 72 to 112 Bar was 110 degrees clockwise on my regulator. Do not forget to loosen the locking screw before adjusting the setscrew and tighten it again after setting the pressure.

Please read the page above here to see why I did NOT use the LG400 regulator but chose the LG300 MK2 16J type regulator for my 16 Joule LG400. I would like to hear any experience you may have with the LG400 regulator.

[Edit 2015: Recently I have received information that advises not to set LG400 regulators at output pressures over 85 to 90 bar. The disc springs inside the reg may be flattened by the increased pressure and lose their spring capacity. Resulting in variable output pressure. When completely flattened they may also scrape the side of the reg cavity and damage the reg beyond repair. Another source said that the output pressure has more variation when you go over the 85 to 90 bar setting.]

LG400 in Action October 4th 2014

Walther LG400 in action. Scope: Leupold Premier 20-50. FT Match Schalkhaar October 4th 2014

How to convert a Walther LG400 to a 16 Joule or 12 footpound Field Target rifle;  a Summary:


What you need:

  • Walther LG300 16 Joule regulator (Walther part number 2693038, I would advise to use Schiesssport Billharz in Germany ).
  • Adapter. To overcome the difference in length between the tube on the LG400 regulator and the LG300 regulator you need an adapter ring with corresponding o-ring.
  • Chrony, chronometer, chronograph or whatever you call these pellet velocity measuring devices.
  • A set of hex keys
  • A regulator tester and clamping tools to adjust the pressure of the 16J regulator (see:Walther pressure regulators )

(I have recently (2015 and 2016) seen quite a few new 16J regulators coming from the factory that have 84 or 85 written on them. You would think the pressure on these would be set to 84 or 85 bar. But when testing them they were all at 75 to 78 Bar output pressure. The 78 Bar will get the energy to a maximum of about 15 Joule or 11 footpound in the LG400.)

What you need to do:

Preventing Point Of Impact Shift / POI shift: What you also need to do is to remove the o-ring / plastic ring (part no. 86 in the drawing above) under the barrel band, and adjust the barrel band so the barrel is fully free floating. It takes some fiddling to get it right. The method I use now is to wrap a strip of printer paper in a double layer around the barrel. Loosen the both bolts on the barrel holder. Slide the paper over the barrel until under the barrel holder and tighten the bolts again. Check by eye if the barrel holder does not touch the barrel.

63 thoughts on “Walther LG 400 for Field Target

  1. Cool stuff Sven ! Thanks for this great page of tech info.

  2. Nothing beats the pleasure that a project like this brings. Congratulations and all the best with the high scores.

  3. Sven, could it be: Current 10m barrel rifling twist is not appropriate for higher velocity ?

    • Hi Peter,
      It is unlikely that the rifling twist is the problem. I did convert three Walther 10m rifles before this one and all gave very good accuracy with the original 10m barrels. My current FT rifle is a converted 10m LG300 with original barrel and it shoots very accurate.
      Gert/Sighter from South Africa also has excellent accuracy with the original LG400 barrels.

  4. Hey, First of all thumbs up for posting your project and experiences!
    I just have some questions and I hope you may be able and willing to help.
    1) That may come of a bit as being a safety sally, but aren’t you concerned that the LG400 might not hold up to the higher pressure in the outlet chamber, as well as the additional stress on the hammer and valve pin?
    2.) I am wondering if you have done any further testing and more information to share!? I am highly interested in the ongoing process of your FT project.
    3.) If you can disperse surely all my concerns of 1.); how can I make you, making one of the small adapter plates for me and ship it to Germany 😀 ?

    Kind regards, Markus

    • Hi Markus,
      To answer your questions:
      1. The LG400 is build up the same as the LG300. The breechblock is largely the same dimensions. And when the LG300 Dominator can stand 100 bar the LG400 will have no problems. I have been shooting the LG400 for quite some time now and so have others. No problems concerning pressure or wear have been reported. The valve in the LG400 is smaller so will have less force from the pressure. The hammer is lighter and so is the hammer spring. No indication of any trouble there.
      2. Follow this website. I will update it regularly.
      3. Yes I can. I’ll send you an email.

  5. I am curious, is the breech block on the LG400 made of aluminum or stainless steel?

    Thanks for interesting post!

  6. 3 things you might wanna do. Install a 22″ walther lg300 “hunter” barrel. Rework the reg pressure to 118 bar. Use 10.6 gr H&N pellets. That will give you 20 ft lb which is legal in the USA. I don’t know about your country so depending on that you adjust the output of your reg. I have done 4 walther lg300’s including a carbontec xt like this and have hit a home run every time. longer barrel is a must for efficiency.
    good luck

    • Hi Vic,
      Thanks for reading my pages and sharing your knowledge. I use my LG400 and LG300 rifles for Field Target competition. The energy limit in these competitions in Europe and according to WFTF rules is 12 footpound (we have no legal max energy in Holland but we shoot according to the FT regulations). So I can not shoot 20 fpe and at 12 fpe I do not need the 118 bar reg setting.
      I agree with you that the air consumption efficiency is better with a longer barrel. And to get 20 fpe from the Walther it may even be a necessity. But at 12 fpe I already get 90 shots from a 200 bar/2900PSI fill in a 200cc cilinder so I do not really need more shots from a fill. And original Walther barrels are quite expensive to buy (223 euro / about 300 USD) so it would ad a lot to the cost of the conversion.
      I’m currently more interested to see if I can get the LG400 to shoot good accuracy with the original LG400 regulator at 100 bar. This did not work when I tried it at first. But I have some new ideas on this but haven’t found the time to source the needed part (weaker valve return spring). If this would be a success the lower cost and ease of conversion would make the LG400 available to much more FT shooters.

  7. Thanks for all your help Sven, my LG400 project is going well thanks to your research and experiments.

  8. Nice page. Really like ur reports and I am looking forward for more testing. Especially if the original reg with <100 bar and weaker spring would show good results…
    Btw: if u prefer the steel cylinders i am willing to change my steel one against your aluminium one. Mine is max half a year old. Thought i would like the weight but dont 😉

    • Hello Markus,
      Thank you for your nice words about these pages.
      About the use of the original LG400 regulator: I have sourced some weaker springs recently (Thanks to Henk v. O. from FT Schalkhaar) to test as a replacement valve return spring (VRS). I’ll post results here.
      For the moment I will keep my aluminium cylinder. I’m still in the setup process so the alu cylinder might be usefull in the future. And I have a spare steel 200cc cil. as well. So no need for an extra steel one.
      Good luck with your own projects, Sven.

  9. Thanks to an enormous amount of support and help from Sven, I can report back that my LG400 conversion has been a complete success, despite the utter rubbish talked by Jon Harris and others about them, it has worked faultlessly since the LG300 16J reg went in. It has been consistent at 778 fps over the chrono for the last 6 weeks. It has grouped well at 50 yards in variable winds.

    Yesterday I shot my first comp with it, a tough 50 shot HFT, the 400 was perfect, any misses were down to poor judgement/fatigue on my part and the need to adjust the stock fit a little more. I had never even used it to shoot a knockdown before, or a kneeler or stander. I filled to 200 bar, shot about 30 in total on the zero range and the 50 shots and still plenty of air in the Junior cylinder, so running efficiently with respect to air consumption.

    Going by my experience, I would recommend the LG400 for HFT, shooters but the carbon fibre shroud should probably be cut down to suit you as it is a bit long.
    If the LG400 reg can be made to perform correctly then that would save a fair amount of expense and messing around, so that is something to keep an eye on.

  10. Great to hear about your success with the LG400. I firmly belief that this rifle in 12 fpe will give the FTP900 a good run for its money. Stable with minimal design changes.
    My next project will be to try and install an extra pre chamber on each side of the original LG400 regulator with its tiny 6fpe chamber. May just be that it will be enough air to get the pellet to 12 fpe.


  11. As always nice report! Heel goed gedaan! ik lez je idereen van je reporten met veel plezier. But since I am German and my dutch is, well you can see…, I tell you in English: Keep up the great work!!

    • Ich danke Dich für das freundliche Kommentar Markus. (You see, my German is excellent 🙂 (with some help from GoogleTranslate 😉

      As for keeping up the work: I installed a softer valve return spring and a 95 bar LG400 regulator on a LG400 breechblock. Currently waiting for the LG400 barrel to arrive. It is on its way. Very curious myself to see if it will get to 16 Joule with 95 bar pressure and how the accuracy is. I’ll keep you posted.

    • Markus,
      Sorry for the belated reply. I dont have a website as such and to beat Sven’ site would be impossible. However, I will post my progress on Pimpmyairgun. At the moment there are two of us who are going to start the development to get 20 fpe/27 Joule out of the LG400.

      First step is to replace the valve and seal to look like the LG300 except for the narrow pin part.


  12. Hi Sven,
    i have a Question, what is Number 46 “Bolzen” for ? I don’t know, but in my opinion the Number 46 Pin doesnt makes any sense for me!
    Can you explain me that? I had Pin 46 driftet out on my LG300XT but there is nothing what i can see in the pinhole, nothing is connected to the pin… by the way the pin is made out of soft metal not hardened, maybe aluminium or brass…

    Best Regards,

    • Hi H.,
      The pin with number 46 is a polymer (POM or nylon?) pin that prevents the hammerspring adjuster screw (no.33) from turning very easily. This way it prevents the pellet velocity from unwanted adjustments. A little more or little less preload on the hammerspring (no.35) would affect the velocity.

  13. Ok, thanks for the reply, but one thing i would know because i want not to damage my LG300XT.

    Can i then turn the No. 33 Adjustment Screw clockwise or anticlockwise without drifting out the No. 46 ? or must i drift the No 46 Pin all the way out to adjust the Screw and after that Adjustment drift it back in?

    • Hello H.,
      That is a relevant question. You can turn the hammerspring adjustment screw without removing polymer pin no.46. The pin will keep doing its job and you will not damage the pin or the trigger block. Only when you are about to do a lot of adjustments back and forth it might be wiser to remove the pin. It does wear a little. After a lot of turning the screw will go very light. When the adjustment screw starts to turn very easily you can always drift out the pin and turn it 90 or 180 degrees. You will then have a new side of the pin touching the screw.

  14. Hi Sven, thanks for the Information.

    When i turn the Hammerspringadjustment-Screw clockwise – how much turns can i do before the hammer slams against the Firingpinground and there is no more effect on the Velocity ??? (I didnt adjust the Reg. because its difficult to open you said… The standard untouched 7.5J Reg is in mine).

    – 2nd Qestion: But when i adjust the Reg what is the Maximum Pressure to set on the Reg and the max Hammerspring Preload to get consistent Results by maximum Power Output with the 420mm Barrel? (Just for: “What Power can the Gun reach?)

    Thank you much for your Help!

    • Hello H.,
      If you have the LG400 rifle the regulator does NOT need to come apart to change the output pressure. Adjusting the LG400 reg is very easy. Its the LG300 regs that are difficult.
      On my LG400 with the LG400 and LG300 reg I got no higher velocity after 1,25 turn clockwise on the hammerspring setscrew. That was from the 7.5Joule setting.

      I never looked for maximum power. I aimed at 16 Joule. But during the testing when I gave the LG400 reg 1 full turn the reg output got to 129 bar! But I never tested this setting for velocity so I have no idea how much velocity 129 bar would give. This high pressure might even give lower velocity because at the high pressure the firing valve is more difficult to open. The LG400 reg set at 112 bar the velocity got to max 240m/s with hammerspring setscrew 1 turn in from 7,5 Joule.

      If your idea is to get the rifle to 21 Joule (280m/s with 8.4grain) I would say you need the LG300 16 joule MK2 regulator because the LG400 reg and doe snot have enough volume. And I guess you should set the LG300 reg at 95 to 100 bar output pressure. (85bar gives about 248 m/s max.)

  15. The LG400 valve system is set up to move 0.5 mm from totally closed to where it cannot open further. The valve seat inside diameter through which the air must go to the pellet is about 4 times smaller than that of a LG300. So delivery of the air required for higher fpe with the LG400 reg is not really possible.

    Wather regs are not able to give a wide range of pressures by adjusting the set screw. Therefore they are made for a fairly tight band. Yes you can get 120 bar out of a 72 bar reg by cranking up the set screw but loose the linearity of the regulation as the 300 bar bottle pressure drops.

    For 20 fpe, if that is what you want, the valve system needs to be adapted. Heavier hammer, larger valve seal id….. and a big pre chamber.

    I am looking into getting my second LG400 to 20 fpe but realised that it will need some serious changes. Time will tell.


  16. 1 Turn to get 129 bar? Hmmm you said above it was 1/2 Turn to get 129 bar? Iam confused.
    But anyway when i set the Regulator to 129 bar and do 1 full Turn on the Hammerspring Setscrew maybe i get 260 m/s ? That would be enough for me for All-Day Shooting.



    • Sorry H. I was wrong there. Half a turn got the reg to 129 bar.
      But I’m not sure if you will get 260m/s with the LG400 regulator at 129 bar. You may even get less power/velocity. As said above (October 5th) the higher pressure acting on the valve will shut the firing valve quicker and reduce the distance it opens. Resulting in lower velocity.
      But you can just try and see. Keep us posted!

      A good way to get an increase in power is usually to fit a longer (22″ to 24″) barrel. In that case you do not have to change the hammer and hammerspring. A new and heavier LG400 hammer would have to be a custom job, hardened and made to a high degree of accuracy. Which would make it an expensive part.

  17. Hi Sven,

    ok it sems to be the best to convert it to 16 J (12 FT/LBS) for now. It is not obvious in your report how much turns i should do to get 112 bar, can you explain me that?



    • Hello H.
      I do not know how many turns on the setscrew the LG400 regulator needs to get from 72 to 112 Bar. I used a regulator tester with manometer to set the pressure. And did not keep an eye on the number of turns needed.
      Keep in mind that Gert found out that the Walther regulators have a small bandwith in which they give a constant output pressure. 112 Bar may be far beyond that bandwith resulting in an output pressure that is not constant over a full charge of air from 300 bar downwards.
      If you do not have a reg tester and are not thinking to make one, it is probably the best to increase the reg in steps of 1/8 of a turn mount it to the rifle and test for velocity at every setting until you arrive at 15 or 16 Joule.

      If I find the time I could test my LG400 reg to see how much adjustment is needed from 72 to 112 Bar. But I’m quite busy at the moment so this could take a week or even more.

  18. Hello Sven that would be great when you could do that for me, i would appreciate it much! Because i do not own a Reg Tester and when you could do it for me i need not to build one for that one time adjustment. I have time to wait until you have done the Job, maybe i can mail you to tell you about my 9003 Anschutz Match Rifle im tinkering at, when you are interestet in knowing about that other Match Rifle for tecnical details.



  19. Original text: “Hi Vic,
    Thanks for reading my pages and sharing your knowledge. I use my LG400 and LG300 rifles for Field Target competition. The energy limit in these competitions in Europe and according to WFTF rules is 12 footpound (we have no legal max energy in Holland but we shoot according to the FT regulations). So I can not shoot 20 fpe and at 12 fpe I do not need the 118 bar reg setting.
    I agree with you that the air consumption efficiency is better with a longer barrel. And to get 20 fpe from the Walther it may even be a necessity. But at 12 fpe I already get 90 shots from a 200 bar/2900PSI fill in a 200cc cilinder so I do not really need more shots from a fill. And original Walther barrels are quite expensive to buy (223 euro / about 300 USD) so it would ad a lot to the cost of the conversion.
    I’m currently more interested to see if I can get the LG400 to shoot good accuracy with the original LG400 regulator at 100 bar. This did not work when I tried it at first. But I have some new ideas on this but haven’t found the time to source the needed part (weaker valve return spring). If this would be a success the lower cost and ease of conversion would make the LG400 available to much more FT shooters.”

    Response: Hi Sven, I agree 110%. Just adjusted the reg on my lg400 anatomic and it is “bang on”. I did however make my own titanium valve spring so maybe that is the season but I have no problems after shooting a tin of HN’s. Thank you so much. YOU ROCK!!!!!!!!!!!

  20. I would however like to add that it is a must to unscrew the cylinder when storing the rifle for more than one week since the increased reg pressure has a deforming effect on the white ptfe o-ring. the you will be all set

    • Hi Vic,
      Thanks for your reply. If i’m reading your post right you are now running the LG400 at 100 bar and getting 12 fpe? And for that you use your own titanium valve return spring?
      I’m a bit puzzled about the white PTFE o-ring you mention. My LG400 only has green o-rings and a black valve seat. So where is this white o-ring positioned?
      Regards, Sven.

  21. Thank you very much Sven! Now i know the Setting for the LG400 Reg-Setscrew!

  22. My bad Sven, I did not explain the white O-ring. I took out the green o-ring and replaced it with the white ptfe ring from the “Hunter”. It fit but not as well as I would have liked so I made one out of white ptfe delrin myself to make it fit it and enlarged the hole to 3.9 MM. If the delrin stats to fail I will revert back to the factory white ptfe. The white o-ring is stable under temperatures and is very robust. However it it has one downside. It retains compression memory if the regulator is kept pressurize over long periods of time. I am not worried because it can handle 100psi but those doing 118 psi should always unscrew the cylinder when storing the rifle for more than 2 weeks. The head engineer at Walther told me to do so. Can you locate the white dominator O-ring? If not, let me know I can send you a couple.

  23. Sven, when I say green, I mean the green outer and the black ptfe inner oring that is in-set within the green. you don’t need to replace the green, Just the black one. To answer your other question, yes I wound my own valve spring but that was just to tinker and do something special. Honestly I don’t think it is any better over the factory one. I however replaced the factory hammer spring with the same length spring but one with slightly higher rating so that I would not have to turn the power cap screw too much in. One more thing, I had two lg 400 regulators special ordered from the factory. I have some friends there who put them together and customized them for me by hand selecting the internal parts. So maybe that has something to do with it. All I did then was follow your directions on this board and so far so good. I am of the opinion that the 400 hammer is too light. Someone suggested that I insert a tungsten rod from the front and pressure fit or glue it in place. Your thoughts?


    • Hello Vik,
      Thank you for your valuable answers. Very interesting. How is the accuracy at 118 bar pressure? (I presume you mean 118 Bar and not 118 PSI. 118 Pounds per Square Inch is only 8 bar)

      To get a heavier hammer you might want to look at the LG300 hammer. From what I can see on pictures it has the same geometry as the LG400 hammer. Looking at the pictures I would say you might need to change the length (grind some off the front part) and it will fit the LG400. You could even try to fit the LG300 hammer directly. The strike distance will be shorter but it is much heavier.

  24. Hello Sven
    Thanks for such a detailed information. That great LG400 of yours looks stunning and more than anything accurate and reliable.
    I was wondering if you would accept to sell some ring adapters.
    thanks Sven

    • Hello Frederik,
      Thanks for your kind words.
      I can make you an adapter. Have made a few for others by now. They are 35 euro plus shipping. That may sound expensive for such a small thing. But it takes me 3 hours on the lathe to make one. The dimensions are critical because it needs to seal airtight.

  25. Hell Sven
    Tanks very much for your, I would not question your price
    Knowing that I van get that one pièce from you I shall nos look in details for a reg
    Thanks again Sven

  26. Hello Sven
    Thanks a lot for your tips I found euroshooting selling the regulator for a decent price, the late Company does not seem to service clients out of regular models.
    I m endavouring my time trying to get the one supplier for all, both for a Lg400 competition with a fitted expert fore end as a replacement to regular mount along with the regulator
    I contacted buingher and hope for a reply
    I will give a try at Benkhedini


  27. Hi Sven
    Can I order that ring from you ?

    • Hi Frederik. Yes you can order the adapter ring for the LG300 regulator. I sent you an email to the discuss the details.
      Thanks, Sven.

      • Hello, congratulations great site! I would like to ask whether it is possible to send the ring and seal regulator lg 300 in the Czech Republic ?? Thank Jirka

      • Hello Jirka,
        Yes I can make you the adapter and supply you with the o-ring to seal it. Will contact you by email to discuss further details.
        Kind regards, Sven.

      • me too, please 😀 dank u well

  28. Свен приветствую,хороший обзор ,мы тоже стреляем LG400 но BR-25 ,есть много информации по данной винтовке ,по воздух регуляторам как его улучшить 🙂 вот ссылка на наш сайт -пользуйтесь Наш сайт

  29. Hello Sven, how are you? I’m fine. I thought about the Reg again. When i use the stronger Hammerspring from the 21J Dominator to open the LG400 Reg when its set to 129 bar, this should be possible, or what do you think? Regards H.

    • Hello Heiko,
      I’m a bit lost and have forgotten: What are you trying to get to? 16 Joule with the LG400 regulator?
      Normally an LG400 standard hammerspring would be enough to open the valve at 129 bar LG400 reg setting. Is your velocity too low?
      I got 240 m/s at 112 bar LG400 reg setting. A weaker valve return spring may be a better solution than a stronger hammer spring. Because you get more vibrations with the stronger hammer spring.
      Regards, Sven.

  30. Hello Sven! I want just to try out what i can reach in power/Velocity with the 129bar Setting.

    • Hello Heiko,
      So you want to see how high you can go 🙂 . I think the power will max out at something around 250 m/s and 17 joule. The small air volume inside the LG400 reg is probably not able to deliver more energy. I think a stronger hammerspring will open the valve faster but not further and a faster opening will only let the same volume of air out more rapidly. Valve opening distance is limited by the length of the valve stem. The regulator is relatively slow and will not be any means keep up with the emptying through the firing valve. But I’m looking forward to your results with the stronger spring.
      One more thing: I recently got information that warned against setting the reg at a output pressure higher than 85 to 90 bar. I was told that the disc springs can flatten out and will be damaged and loose their strength. These flattened springs are larger in outside diameter and may also scratch the walls of the hole that they are in. They will then damage the reg beyond repair. I do not know if this is true. And I do not know at which output setting it will occur. But you are warned now!.
      For anybody that wants to convert an Walther LG300 or LG400 rifle to 16 Joule / 12 FPE I have only one advice: USE THE 16 JOULE MK2 REGULATOR SET AT 80 TO 85 BAR!. This is the proven setup. I myself and others are using this setup for over 1,5 years now without trouble. You are of course free to do what you like yourself and it may work as well.

  31. Hello Sven,
    thank you for the notice about the danger of setting the pressure too high.
    I will then set the Pressure to 90 bar, then its in the save range.
    Who has you warned about these facts?

    Thank you!

  32. Hi Sven having read your lg 400 convention to 16 j i am going to do the same,could you make me the adaptor please.Thank you Martin G

  33. Hi Sven,
    Would you be able to supply me with Adapter and O-ring for the above conversion. Email me with payment details.
    Kind regards, Karl

  34. Hi Sven,

    I am in the process of purchasing a LG400 and would like to convert to 16 joules. Please could you supply me with an adaptor and o ring.

    Many thanks, and Happy New Year,

  35. Hi Sven,
    See here: – will be great if you can get your hands on this in Netherland from a club mate, or sample from Krale-Schietsport (just informed Gerrot) and compare barrel performance and any other gremlins you can find…if they are willing to loan you for a review


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