Airgun Accuracy

Only accurate airguns are interesting!

Walther LG 400 Hammer Bounce

This movie shows the underside of a Walther LG 400 breechblock. When the hammer is released (at 49 seconds into the movie, sorry for that) you can see it bouncing 2 or 3 times. Each bounce opens the valve and releases some air that is not effectively used to propel the pellet because this has already started off in the barrel. Reducing hammer bounce can save a lot of air and increase the number of shots from an aircylinder fill. I made an anti bounce hammer for my Airarms S400 FAC which increased the shotcount from 38 to 68 shots per 200 bar fill.

Walther LG 400 Hammer Bounce movie  

Unfortunately photobucket does not support this link anymore.

 

 

 

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7 thoughts on “Walther LG 400 Hammer Bounce

  1. how much is it

    • How much is it? You mean to buy a Walther LG400? Not knowing where you live makes this a difficult question. I’d suggest you do a google search. For Germany retail prices can be found here: http://www.hasselhorst.de/?seite=lieferprogramm&kategorie=6 . The LG400 Alu stocked Economy version is 1560 Euro/1750 US Dollar/1126 British pounds. The cheapest LG400 is the alu stocked LG400 Blacktec version for 1240 euro/1390 USD/895 British pounds (all google currency converted prices). But there are many shops available in Germany and around the world that will sell and send you the LG400.

  2. Can you explain how you did the anti bounce hammer?

    • Hi Michael,
      My anti-bounce hammer is for the Airarms S400, not for the Walther rifles. It is an hammer made of two parts that slide over each other. The inner part is made from bearing bronze and pushed by the hammer spring and slides over the hammer rail. The outer part is shorter and, is pushed forward by the longer bronze inner part. When the inner part hits the front, and comes to a stop, the outer part slides forward and hits the valve stem. The outer part will not bounce because it is not in contact with the hammerspring.
      I have a drawing somewhere, will post it here. I noticed that the original thread on the Airarms Owners Club forum has been deleted.

  3. With regard to hammer bounce, I have had some issues with this.

    After my recent annual strip and clean I decided to run at slightly higher FPS than usual to see how it worked out. I set it to 787-790 with 8.4s. It grouped well and I shot a couple of comps. I noticed the odd flyer which never happened before then getting to the end of the 30 shot courses, the last couple dropping low. I charge to 200bar. The charge after 15 zeroing + 20 comp shots was 70bar!!!!!!!. My companions noticed a lot of air blowing leaves around from the stripper after each shot.

    When I got home I observed the hammer in action and it did seem to bounce a lot, so I reset it to 770-775. Now it is back to 100 shots from 200 bar to just under 100bar.

    Bear this in mind when winding up the hammer spring please!!! Once you go past the sweet spot for this lightweight hammer assembly, all you are doing is adding spring pressure and bounce for no gain in M/V.

  4. Thank you for the valuable comment Roger.

    I was told about the same situation by a Dutch shooter recently. The thing is that the LG400 usually has two setting of the hammerspring that give the same velocity but a different air consumption.

    The LG400 can be set to a higher velocity than 775 fps but keep in mind: There usually is a setting that delivers 785 to 790 fps (240m/s) at a very low hammerspring preload and a setting at a higher hammerspring preload that delivers the same velocity. The high preload setting uses much more air and is more sensitive to changes. The higher air consumption being caused by more hammer bounce.

    The best thing to do when adjusting the velocity is to start with the hammerspring setscrew turned almost all the way out. So that it is level with the rear of the action block. And then slowly turn it in (clockwise) with 1/8 of a turn while shooting it over the chrony. When you come near the desired velocity (starting at 755 fps or 230 m/s) go to adjustments of only 1/16th of a turn. My desired velocity for accuracy has always been 236 m/s (774 fps). But I know people that run the LG400 at 240 m/s (787 fps) and also have good accuracy.
    A quarter of a turn is too large an adjustment and you can easily pass the optimal setting.

    At the optimal setting the adjustment is also much less sensitive to spring preload changes that may be caused by temperature, lubricant, dirt or spring fatigue.
    But the main thing is to stay at a low preload to reduce air consumption and also to prevent unwanted velocity changes because the spring preload changes.

  5. That’s great information Sven. I will go to the club on Saturday and adjust over the chrono just like you said.

    It really was confusing why I had run out of air. Glad to say in the years of outside shooting with the Lg400 there have been no mechanical failures only operator error 🙂

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