LG Striker Bounce

Discussion in 'Steyr' started by cloverleaf, Mar 25, 2019.

  1. cloverleaf

    cloverleaf Active Member

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    There are many things I like about my LG110; sadly its ear-splitting muzzle report and medicre air consumption aren't among them.

    Thanks to many of the things that make the design so technically proficient in some areas, the LG really suffers from striker bounce - the graph below shows an audio recording of a firing event taken at both the action (top channel) and muzzle (bottom channel). For reference the rifle tested is my LG110 optimised with a 4mm port and standard 85bar reg pressure.

    [​IMG]

    Observing the bottom channel as this most obviously illustrates the issue we see a small initial spike corresponding with air in front of the pellet evacuating the barrel, following this is the muzzle report "proper", followed by a series of 7-9 additional spikes caused by the air released as the striker and valve gear oscillate after the shot.

    Most guns suffer from this problem to some extent; indeed in designs with long-stroked, heavy strikers this can be detected as a distinctly raspy / farty muzzle report; however in this case the oscillation is at such a high frequency (around 400hz) that our ears perceive it as a single loud blast.

    Most other guns I've tested give between two and four instances of bounce (other than the electronic Daystates and Steyr H5A which exhibit none!).

    I reckon killing striker bounce could improve efficiency and shot count by as much as 50% as well as making the guns much easier on the ear.. the big question of course is how to achieve this.

    There are various approaches to this problem already in production (although in truth most manufacturers seem to ignore it); the big issue in my mind being how to implement a workable / adjustable system without making any irreversible changes to large parts of the rifle - i.e. the striker housing, stock or chassis.

    Unfortunately Steyr did such a good job in packaging the striker assy that it leaves very little space to add a debounce device... anyone got any ideas they'd like to share? :p
     
  2. sportsmatch

    sportsmatch Member

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    At over 100 shots on my 3 I just shoot them no microphone nothing
     
  3. SteveC200

    SteveC200 Active Member

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    Have you tested any mechanical Daystates with slingshot hammer? Presumably this is the sort of thing you want for the Steyr, just much more compact?
     
  4. cloverleaf

    cloverleaf Active Member

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    I've tested a Huntsman Regal which looked better but not perfect with one spike resulting from bounce; there may have been smaller instances too but I couldn't remove the shroud to test it so the results are somewhat attenuated.

    The slingshot system doesn't work particularly well to quell bounce (although does have other benefits). It becomes better at killing bounce the heavier the "inactive" carrier is relative to the mass that actually strikes the valve. Unfortunately increased mass here also requires more input spring energy; which is all wasted slamming the carrier into the valve body / rifle's action. I'm not averse to implementing such a system in the LG for the other benefits it brings, although I think as an anti-bounce device it's a bit of a dead duck tbh (at least on its own).
     
  5. SteveC200

    SteveC200 Active Member

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    A couple of ideas, dont know if theyve been done before, probably have. First off, a damper to absorb the secondary bounces? Soft enough to allow full opening of the valve on the first strike but stiff enough to to stop the hammer afterwards. Maybe just a soft O ring around the firing valve pin? Secondly, have a sear that catches the hammer after the initial strike. How that could be made to work I have no idea. :)

    Out of interest which of the electronic Daystates did you test? I've been using my Mk3 shooting FT for years, I think they are seriously under rated.
     
  6. RobF

    RobF Administrator Staff Member

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    How would an o-ring around a valve stem work? Surely that would just add friction to the valve and all the variation that brings?
     
  7. C.Eaton

    C.Eaton Confirmed Anschutz Nut...

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    I've always wondered if a rotating valve would work better than the knock open design of the past thirty years. Even something as simple as a sprung loaded rotating spindle with a hole drilled through it. On pulling the trigger the spindle rotates say 90 degrees going from shut off, to fully open to shut off in a fraction of a second. No hammer, less delay because of it, viable?
     
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  8. RobF

    RobF Administrator Staff Member

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    how does it seal?
     
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  9. SteveC200

    SteveC200 Active Member

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    Quite possibly. Or use one marginally larger that the stem so it doesn't touch. It'll need securing somehow, machining a groove for it to sit in would be the proper way to do it I guess. Or glue it to the end of the hammer maybe?

    How much does the firing valve open on the initial strike and the subsequent ones?
     
  10. SteveC200

    SteveC200 Active Member

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    So basically a tiny ball valve?
     
  11. C.Eaton

    C.Eaton Confirmed Anschutz Nut...

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    Yep, I'm sure someone has tried it at some time.
     
  12. cloverleaf

    cloverleaf Active Member

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    Cheers guys!

    To systematically address and shoot down all of your suggestions... :p

    A damper is a great idea but it requires a mechanism for its selective engagement between the first and subsequent valve strikes. Unfortunately you can't just stick something in there in the hope that it won't affect the first strike but will kill subsequent impacts!

    You could in principal have a mechanical device that impinges on the striker under bounce to limit its travel; but again it's very difficult to implement in the existing Steyr design.

    Some people have advocated this approach as a way of limiting valve lift; for all the potential benfits that brings..

    Workable in principal if everything's perfect, but in reality killed by the the fact that such systems never seal 100% - which is obviously a must in our situation.

    I too have wondered on to thoughts of alternative valve formats - but ultimately come back to the fact that teh humble poppet has been used for so long by so many with good reason!
     
  13. RobF

    RobF Administrator Staff Member

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    If it doesn't touch what does it do?
     
  14. SteveC200

    SteveC200 Active Member

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    Umm, the topic of conversation. Which has now been shot down by Mr Leaf.

     
  15. RobF

    RobF Administrator Staff Member

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    I’m just trying to understand what you weee suggesting which was something should sit on the valve stem but then not.
     
  16. Adam

    Adam Well-Known Member

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    How about a little inertia weight inside the striker like in the theoben gas ram pistons?

    I guess most of the solutions proposed would be along the lines of the ideas to stop piston bounce in springers, just massively scaled down. And like in the springers I guess the only real solution is balancing everything optimally to minimise bounce. “Tuning” in the proper sense of the word.
     
  17. SteveC200

    SteveC200 Active Member

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    As I said, its just there to absorb secondary bounces of the hammer. If it worked (which it seems it wouldnt) it would sit around the firing pin because thats where the hammer hits. :) An O ring was just off the top of my head. I cant picture how far the firing valve stem pokes out and I dont know what the valve stroke is either so it was very much just throwing an idea out.

    [​IMG]
     
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  18. C.Eaton

    C.Eaton Confirmed Anschutz Nut...

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    Maybe a modern take on the ‘sling-shot’ concept but smaller in form?
    Or...how about a design where there is a small back-lash of air through the valve that actually pushes the hammer back away from the valve stem?
     
  19. RobF

    RobF Administrator Staff Member

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    Yep, that would cause a lot of inconsistency dragging on the firing valve unfortunately.
     
  20. RobF

    RobF Administrator Staff Member

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    There always is. The valve stems always leak. But you'd need a hell of a lot to push back the hammer, and what happens when the valve closes? The problem isn't the push back against the hammer, it's the hammer bouncing off the spring and coming back and hitting the valve again.

    Somewhere on here I video'd the Walther doing it in slow motion.
     
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