Tuning Vs Performance

Discussion in 'Piston & Spring' started by skires, Oct 9, 2018.

  1. Cooper_dan

    Cooper_dan Well-Known Member

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    A welcome voice of reason in the current 'tuning' frenzy!
    I've shot most of the 'super tuned' springers and none had me reaching for my wallet. They just arent that different from a smooth shooting 25mm, and definitely dont infer some kind of advantage. Highest single springer score in last years UKAHFT was with a 25mm mk2 tx200.

    But when i tell people this they tend to go and get a mega tune anyway :rolleyes:
     
    Last edited: Jan 15, 2019
  2. FPoole

    FPoole Active Member

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    I just shot my other "super tuned" TX this afternoon. It's a MarkII and has the MarkI/II piston with a blue Maccari seal. The comp. tube end plug has been trimmed to get 3 mm extra stroke and shorten the transfer port. Easy cocking, but not as easy as the MarkIII, and it's calm enough for me. I still would like one of the really special kits, but it takes me a while to go ahead and do something.
     
  3. nurek

    nurek Member

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    You have summed it up well above, my question is, what does that do to 'piston bounce'? It will be more efficient, shoot faster, but does it also recoil more?
     
  4. Adam

    Adam Well-Known Member

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    Recoil (rearward movement when piston going forward) will be less due to lower piston mass. Surge (forward movement when piston bounces back) CAN be greater if the port diameter is too small. Which is why a small bore conversion often includes widening the port.
     
  5. skires

    skires Well-Known Member

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    I think that those that have been in the game of shooting springers for long enough ( and it's the same for PCP to be honest ) know that there isn't any crutch. There is no magic secret passage that projects you 1 or 2 years ahead in advancement. There is no quick fix.

    The only real way to better scores is to get to know your kit and put the hours of practice in. Notice what you are weak at and put the practice in to improve those areas.

    It's human nature to:-

    Want that quick fix. Want that jump ahead of the game.

    Wonder if the bloke next to you has something better than you have and thus has an advantage over you.

    Just simply want to start off with the best that you 'think' money can buy.

    These things are plentiful in the worlds of FT and HFT and all other amateur sports that I see in the UK. Meanwhile the folk at the top of the performance charts are those that learn their kit, learn the sport, and put a shift in.

    A great Aussie test player talking to young Aussie test cricketers ... ( Add your own Aussie accent ) ...

    " Do you want to know the three secrets to being a great test player lads?"

    "Number 1 ... You work bloody hard"

    "Number 2 ... You work bloody hard"

    "Do you want to know what number 3 is?"
     
    Last edited: Jan 18, 2019
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  6. hmangphilly

    hmangphilly Floppy Quick Phil

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    The piston doesn't necessarily have to be either smaller or lighter to get down the comp tube faster Neil .
    And is faster always better ?

    A good few shooters have removed short stroke lightened pistons , describing them as 'snappy '.
    I assume that means too fast ???
     
  7. Nick G

    Nick G Active Member

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    It all depends on how you like them, I tune my guns so you can see where the shot lands , this helps when shooting in the wind obviously, and when setting up, the advantage imo of a smaller diameter tune is they are faster with less movement , but feel softer and more civilised than a short stroke 25mm, not all though , if you go too long on stroke in say a 22mm they shoot very similar to a standard Mark 3. I too have shot lazer glide guns , and comparing one to my own prefered tune is like chalk and cheese , ok they are super smooth but far too much movement for me .
     
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  8. Adam

    Adam Well-Known Member

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    Newton's 2nd law ... f = ma
    (Force = mass x acceleration )

    To get down the comp tube faster (ie accelerate faster) does needs a lighter piston or more spring. Or finish the journey quicker by making it shorter overall (short stroke).
    It's the faster acceleration from more spring that leads to the "snappy" feeling. The overall shot time isn't necessarily any quicker.

    But no, faster isn't necessarily always better.
     
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  9. RobF

    RobF Administrator Staff Member

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    That's interesting. We had a rig that I didn't like because it felt too fast, too snappy... i'm pretty sure we pulled the stroke out before doing anything and it still felt too fast and snappy. So we put some weight on the piston and voila, nice feeling again.

    What I'd like to do is measure the 'volume of the recoil'... by that I mean the amount of time vs the force back... because if the spring and stroke are consistent then my thinking is the force back is the same, but the time period could be different with a different weight piston... so you either have short but 'spiky' recoil, or slower but softer sensation. The area under the graph is the same. Or that's my theory. Jim would probably pour some actual maths and knowledge on that to say if it stands any scrutiny... my graph maths is pretty poor unless someone takes me by the hand.

    When we were mucking around with PCP's a few years back we discovered that you could alter the feel by the valve closing behaviour... not news to some, but to us it was... I likened it to being hit by a pillow, or a thin metal bar of exactly the same weight... the force is the same but the hit is different.

    That brings me neatly back full circle to the difference between tuning and performance. Performance is the numbers, it will still do 795 fps, with the same spring, the pellets will still have the same accuracy down range from the gun. But how it feels to you is the tune, like setting suspension for a particular corner or circuit on a bike or car. The vehicle still has the same BHP, but it's able to put it into the tarmac better, thus you go faster. If you put it on a rolling road however the suspension doesn't alter the peak power.
     
  10. Conor

    Conor Never been banned from sales Staff Member

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    What’s number 3?
     
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  11. garym

    garym Active Member

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    Maximum mag. Then work bloody harder. ;)
     
  12. skires

    skires Well-Known Member

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    I think this is the crux of the matter that is shining through this thread now ...

    It's what you get used to and what you find suits you. I've always had my 77s set up in 25mm with fast and snappy actions. So Venom or V-Mach like.

    I totally accept now from a ... er ... technical or engineering stand point, that the springs on those have wire that is too thick and the springs too short, to give as minimal feel of recoil as the tunes with the softer and longer springs. I've read too much from Jim and Bigtoe, and respect their comments too much, to ignore that.

    However ... I still like the feel of those fast and snappy 25mm 77s more than anything else I've tried. Maybe if I tried one of the softer feeling springers ( or softer tunes ), and shot it for a couple of years, I'd see an improvement in my shooting. I've never given one a decent time run.

    In Tingles of Stoke in the 'Naughty Room' there's a ten quid difference.
     
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  13. Adam

    Adam Well-Known Member

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    See, it's local knowledge like this that makes the forum so great! ;)
     
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  14. Nomads HFT

    Nomads HFT Well-Known Member

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    Can't help with the graph, Rob, but possibly with the effects of reducing piston mass.

    The air is compressed by the momentum of the piston and spring. Momentum is the product of mass and velocity so, if you reduce the piston mass and that alone, the lesser mass will increase the initial piston acceleration (it will feel a bit faster), but the reduced momentum will result in the air being less compressed, normally reducing muzzle energy. This will result in slightly sharper recoil acceleration, and slightly less displacement.

    If you also increase the spring force to compensate for the reduction in mass and to maintain piston momentum and muzzle energy, the compression stroke will be faster still. This will result in significantly sharper recoil, but with the same displacement as you started off with.
     
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  15. Scott Hull

    Scott Hull Member

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    What is meant by "sharper recoil"?

    Do you mean the recoil magnitude? Because a change in piston mass should not affect that. And by "recoil", I'm assuming that you mean the rearward push of the gun. The result of a lower piston mass would be a recoil of the same force magnitude, but with a shorter time duration.

    If we reduce the piston mass, the time duration is reduced, and the "volume of the recoil" (area under the force-vs-time curve) is reduced accordingly.

    Though "volume" is a three dimensional unit, so "area" might be a better term.
     
    Last edited: Jan 19, 2019
  16. Nomads HFT

    Nomads HFT Well-Known Member

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    "Sharper recoil" is how people seem to describe the sensation of faster acceleration, Scott.

    "Recoil" describes the rearward rifle movement (and many now use the term "surge" to describe the following forward motion).

    Reducing the piston mass usually reduces the piston displacement (apparent from reduced muzzle energy - it's not something that I can directly measure) which, in conjunction with the change in the ratio between piston/spring mass and the mass of the rest of the rifle/scope, reduces recoil displacement, which I can measure. I am able to measure recoil velocity (I can also measure acceleration, but prefer velocity), and integrate the data to arrive at the recoil displacement.
     
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  17. Neil-T

    Neil-T Boingers forever.

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    My stock fits me perfectly, so my head is in the same place everytime I put my cheek on the cheekpiece, I use a fixed 40 mag leupold comp and never struggle to find a target. Warren Edwards TX stock made to fit. Since the end of August last year I've gone back to standard internals as I had no choice when my rifle had a few problems during the Worlds in Poland. All that was available from good friends who took spares was a standard kit. The rifle is not the sweetest thing to shoot, and I have others which shoot smoother and are tuned. Nick G and Nick Murphy tuned TXs amongst them. But for some reason I can't explain....could be skill....lol. I'm shooting better now than ever before, putting AA scores in on a regular basis in this season's MFTA Winter league. So my conclusion is a rifle that is tuned and shoots as sweet as anything with little recoil is no more accurate than a standard one. Just stick with one Springer and learn it.
     
  18. Scott Hull

    Scott Hull Member

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    So:
    sharpness of recoil would be determined mostly by, (spring force)/(gun mass), correct?

    For total free-recoil gun displacement, I use this:
    gun displacement = stroke x (piston mass)/(gun mass)

    Piston mass would include any tophat and 1/2 of the spring mass.

    My gun is fairly snappy. I'm currently experimenting with additional gun mass and just shot a match with it at 17lb. It is heavy but comfortable enough. I'm currently running:
    25mm piston
    74mm stroke
    241g active piston mass (176g piston, 10g tophat, 0.5 x 110g spring)
    .740" OD spring, .118" wire diameter, 40 total coils (closed and ground on both ends), rate = 29 lb/in, 3.5" of preload
    90A durometer Viton o-ring piston seal
    Krytox lube
    Input (spring energy) = 36 foot-lbs.
    Output (pellet energy, 8.44gr@790fps) = 11.7fpe
    efficiency = 11.7/36 = 33%

    That is at sea level. I can get a few points better on the efficiency by using a lighter pellet or a heavier piston. So there is probably a little bit of piston bounce going on. Since I shoot at some higher altitude venues as well, I feel that accepting some reduced efficiency and a little piston bounce is OK when shooting at sea level. It reduces the onset of piston slam when shooting at higher elevation venues. If I only shot at sea level, I'd likely increase the piston mass a little, and reduce the spring energy a little.

    I have never played with the piston diameters smaller than 25mm.
     
  19. Conor

    Conor Never been banned from sales Staff Member

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    Not bad from a guy who believes in the imaginary “ricochet reset”! :D:eek:
     
  20. Cooper_dan

    Cooper_dan Well-Known Member

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    Yesterday a couple of us hung around after a shoot and played with springers.
    There was:
    Mk2 tx in home modified stock
    25mm hw97 in ginb stock
    Standard Hw95
    22mm 97 in standard stock
    Titanium piston 97 in a big target stock

    Obviously they all felt different but after a couple of shots i could hit the 45 yard spinners with all of them. The easiest to shoot were the tx (my own stock) and the ginb 97. The 22mm 97 had very little sight picture movement but the standard stock made it harder to hit the spinner repeatedly. The 95 was the same.
    Unfortunately the titanium piston 97 didnt have a scope but the warren edwards stock felt very comfortable and repeatable and im sure would have been equal to the ginb.

    Morale of the story. Stock fit is more important IMO
     
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