I had the opportunity to test three different pressure regulators that all fit the Walther LG300 and LG400 rifles. The regulators were tested for dependency of the input pressure, response time and muzzle velocity.
The Walther regulator is a the original 16 joule LG300 mk3 regulator. In the past I had found that the output pressure of the Walther regulator (reg) is influenced by the input pressure (say cylinder or reservoir pressure). On a few Walther regs that passed by my workshop I have seen an output pressure change of up to 10 bar over a cylinder fill of 200 to 100 bar. (But this change in reg pressure did not seem to have a great effect on the muzzle velocity, see at the bottom of this page).
This finding kept me thinking and when I got the chance to get my hands on a Steyr reg that can be fit to a Walther rifle (many thanks Hmangphilly) and a Korick reg (thank you Arne) I did not hesitate to get those home. I hoped that these regulators would give a more stable output pressure compared to the Walther reg and as a result an (even) more constant pellet velocity.
I tested 2 Walther regs and the Korick and Steyr regulator on my Swiss made Keller LEO 2 digital manometer that was fixed on my own make regulator tester. This reg tester has a firing valve to cycle the reg just like it would on a rifle. The velocity tests were performed on my Walther LG300 rifle which has all original Walther parts. This was originally a 7.5 joule (6 ft/lbs) 10 metre rifle and thus has a 420mm barrel. The only things changed are the regulator and the valve seal which were replaced by the 16 joule reg and the white PTFE seal from the Walther Dominator. (it is the rifle on this page)
The Korick regulator is made by Joe Korick (see http://korickdesigns.com/blank_004.htm ). It is said that he also designed the regulators that Air Arms used for the Pro-Target and EV-2 rifles (source: https://www.airarmsanorak.co.uk/air-arms-rn10-pro-target .)
The Steyr regulator is from the Steyr LG100 and LG110 rifles. It is quite small in size compared to any other pressure regulator (Walther, Korick, Air Arms, HUMA, Lane) which makes it easier to fit it to different rifles. It is also relatively cheap and easy to service (when you know what you are doing !).
The Results; Output pressure
First result of the tests is the effect of reg input pressure on reg output pressure. I charged three air cylinders with 100, 150 and 200 bar respectively and connected these cylinders to the regulators. I cycled the regs three times and after that read the output pressure after 15 seconds.
Table 1. Regulator output pressure at 100, 150 and 200 bar input pressure
| Reg Input Pressure (bar) | 100 | 150 | 200 | Max. Difference | |
| Walther reg A output pressure | 79.8 | 83.3 | 87.4 | 7.6 | bar |
| Walther reg B output pressure | 81.3 | 84.2 | 91.4 | 10.1 | bar |
| Korick output pressure | 92.4 | 88 | 84.1 | 8.3 | bar |
| Steyr output pressure | 90.2 | 90.4 | 90.9 | 0.7 | bar |
The chart and the table show that the Steyr regulator is by far the most stable, and thus does its job in regulating pressure the best. It has a difference of only 0.7 bar over a cylinder fill between 200 and 100 bar. In the Walther and Korick regulators the pressure changes between 7.6 and 10.1 bar over a 200 to 100 bar cylinder pressure.
Results; Regulator response time or Reg creep
I also looked at the time it took the 3 regulators to reach their output pressure. In the previous test on the reg tester I noticed that the Korick and Walther regulator kept showing an increasing pressure the longer I waited. This phenomenon is also named ‘creep’. This may be important because in a field target competition the time between shots varies a lot. Between targets on a lane it is maybe 1 or 2 minutes. But when the shooter goes to the next lane the time will be much longer and when there is a cease fire the time between shots can be very long. A long reg response time will mean that the pressure that is used to fire the shot will be different, depending how long the time between shots is.
Table 2. Regulator response in bar per 2 minutes
| Walther RegA | Korick 8.37mm | Walther RegB | Steyr Reg | |
| pressure change over 10 minutes (600sec) | 0.85 | 5.4 | 1.6 | 0.3 |
| bar/2 minutes | 0.085 | 0.54 | 0.16 | 0.042 |
The Korick regulator takes a very long time, 10 minutes, to reach the end pressure and the Steyr reg is very fast. In 30 seconds it is at its end pressure. In table 2 I expressed the pressure change in bar per 2 minutes. This may give you an idea of what happens to the pressure between 2 shots in a competition (as the WFTF regulations say a shooter has 3 minutes for 2 targets per lane with 1 minute preparation time).
Let me add that I ‘tuned’ this Steyr reg a bit. Before the tuning it was less stable and had a 1.1 bar creep in 4 minutes (0.55 bar/2 minutes like the Korick reg. But the Steyr reg reached the end pressure at 4 minutes, after that it was stable unlike the Korick). I took the Steyr reg apart and turned the piston sealing surface on the lathe to get a new and smooth surface that would meet with the shut off screw without any leak. I used Krytox as a lubricant for the o-rings to get a quick response of the reg. Then I set up the output pressure by shimming instead of turning the setscrew on the front. (I learned about this from this thread on Shooting-The-Breeze.com: https://shooting-the-breeze.com/threads/steyr-regulator-a-before-and-after.41076/
Results; Pellet velocity at the 3 different cylinder pressures
The final result of this test is the measured velocity of the pellet at the muzzle of the rifle. I used the same tin of JSB Exact 8.4 grain 4.52 head size pellets for all testing. The chronometer I use is from Airchrony and the rifle was in the same position for all testing. The chronometer was connected to a computer to register and store the velocities. I used three air cylinders filled with 100, 150 and 200 bar respectively and connected those in turn to the regulators. The cylinders where filled from a 10 liter 300 bar pressure cylinder to the mentioned pressures before each different reg was tested. After connecting the cylinder to the regulator two shots were fired without a pellet to cycle the reg and give it chance to settle itself at the new input pressure. After that 10 shots were fired over the chronometer and used for the charts and tables published here.
Chart 3
The chart above shows the results. The first thing that we see is that the velocity achieved with the different regs are not the same. The Walther regulator gives a 4 m/s (13 fps) lower velocity probably because its output pressure (87bar) is set lower compared to the Steyr reg (91 bar). The Korick reg was set at 84 bar but gives velocities equal to the Steyr at 91 bar. I have no idea what caused this. Can be that the Korick reg has a larger internal volume or a faster flow trough the reg which helps to achieve higher velocities.
The chart may look somewhat complicated because it tries to show not only average 10 shot velocities with the lines in the chart (blue=Walther, red= Steyr, green=Korick) but also minimum and maximum velocities with the T-bars and the quartiles with the boxes. (it is the ‘box & whisker’ chart from Excel)
To me the most striking observation is that all three regulators keep the velocity within a 3.10 to 3.70 meter per second difference (10 to 12 fps) over 30 shots. This means that the measured regulator output difference of 0.7 (Steyr) to 10.1 bar (Walther) does NOT have an effect on the pellet velocity!
Apparently the rifle is self regulating which takes away the effect of a lower regulated pressure. We know this from un-regulated PCP rifles like the Air Arms S400. Unregulated rifles have a so called ‘sweet spot’ were many shots reach a very close velocity independent of cylinder pressure. (30 to 60 shots with 5 m/s spread depending on the rifle type and cylinder capacity)
When we look at table 4 with the data of all the shots over all pressures tested we see that the Walther regulator, with the largest difference in reg output pressure, has the lowest extreme spread in pellet velocity over 30 shots.
Table 4. All data of the velocity at 3 different input pressures
| LG300 no. 18936 with | Walther reg | Korick reg | Steyr reg |
| Pressure (bar) | Walther Velocity (m/s) | Korick Velocity (m/s) | Steyr Velocity (m/s) |
| 100 | 226.5 | 231.7 | 231.7 |
| 100 | 226.5 | 231.2 | 231.7 |
| 100 | 227.0 | 231.7 | 231.2 |
| 100 | 226.0 | 231.2 | 232.3 |
| 100 | 226.5 | 231.2 | 229.6 |
| 100 | 226.5 | 229.6 | 231.2 |
| 100 | 225.8 | 229.6 | 231.2 |
| 100 | 226.0 | 231.2 | 231.2 |
| 100 | 226.5 | 230.1 | 230.1 |
| 100 | 226.5 | 231.7 | 231.2 |
| 125 | 232.3 | ||
| 125 | 231.2 | ||
| 125 | 231.2 | ||
| 125 | 231.2 | ||
| 125 | 231.2 | ||
| 150 | 225.5 | 232.3 | 230.1 |
| 150 | 226.5 | 230.7 | 231.2 |
| 150 | 231.7 | 231.2 | |
| 150 | 227.0 | 232.3 | 231.2 |
| 150 | 225.5 | 231.7 | 230.1 |
| 150 | 226.5 | 230.7 | 230.7 |
| 150 | 225.5 | 231.7 | 230.7 |
| 150 | 227.0 | 231.2 | 230.7 |
| 150 | 228.6 | 232.3 | 231.2 |
| 150 | 227.0 | 232.3 | 231.2 |
| 200 | 227.0 | 232.8 | 231.2 |
| 200 | 227.0 | 230.7 | 229.1 |
| 200 | 226.5 | 230.1 | 230.1 |
| 200 | 228.6 | 230.1 | 228.6 |
| 200 | 227.6 | 231.7 | 229.6 |
| 200 | 227.0 | 230.7 | 231.7 |
| 200 | 226.5 | 231.7 | 231.2 |
| 200 | 227.6 | 230.7 | 231.2 |
| 200 | 227.6 | 230.7 | 231.7 |
| 200 | 227.6 | 231.7 | 230.7 |
| reg output pressure (bar) @200 bar input: | 87.4 | 83.5 | 90.9 |
| average | 226.8 | 231.3 | 230.8 |
| min | 225.5 | 229.6 | 228.6 |
| max | 228.6 | 232.8 | 232.3 |
| Extreme Spread | 3.10 | 3.20 | 3.70 |
| Standard deviation | 0.78 | 0.77 | 0.82 |
When the velocities of the 10 shots are averaged over the input pressure the figures change somewhat:
Table 5. Average 10 shot velocities over 3 different input pressures.
| Reg Input Pressure (bar) | Walther regB Velocity (m/s) | Korick Velocity (m/s) | Steyr Velocity (m/s) |
| 100 bar | 226.4 | 230.9 | 231.1 |
| 125 bar | 231.4 | ||
| 150 bar | 226.6 | 231.7 | 230.8 |
| 200 bar | 227.3 | 231.1 | 230.5 |
| average velocity | 226.7 | 231.3 | 230.8 |
| min velocity | 226.4 | 230.9 | 230.5 |
| max velocity | 227.3 | 231.7 | 231.1 |
| Extreme Spread velocity (m/s) | 0.9 | 0.8 | 0.6 |
This table shows that the more consistent Steyr regulator has a lower spread in velocities. Averaging the 10 shot velocities reduces the effect of the pellet on the velocity. That is the reason this table shows the relation between stability of output pressure and pellet velocity. The regulator with the most stable output pressure has the lowest spread in pellet velocity and vice versa.
But the conclusion remains that the regulator stability of output pressure has very little effect on pellet velocity. There is only a 0.9 m/s (3 fps) variation in velocity from a regulator that has a 10 bar variation in output pressure.
Concluding I would say that a well set up field target rifle does not need an regulator which is extremely stable in output pressure or response time.
| Reg Input Pressure (bar) | Walther regB Velocity fps | Korick Velocity (fps) | Steyr Velocity (fps) |
| 100 | 742.7 | 757.6 | 758.3 |
| 125 | 759.3 | ||
| 150 | 743.3 | 760.1 | 757.3 |
| 200 | 745.7 | 758.2 | 756.3 |
| average | 743.9 | 758.8 | 757.3 |
| min | 742.7 | 757.6 | 756.3 |
| max | 745.7 | 760.1 | 758.3 |
| E.S. | 3.0 | 2.5 | 2.1 |
Airgun Accuracy 