Springers & temperature

Discussion in 'Piston & Spring' started by Nick G, Nov 19, 2019.

  1. Nick G

    Nick G Active Member

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    I took advantage of the first cold snap this morning, to see if the cold affected my TX 200 tune , Luckily I had one action in the garage : cold +1 degree, and another in the house warm +20 degree, both guns have aluminium pistons and aluminium ( hard anodised) comp tubes with x ring seals lubed with krytox, one has a slightly longer stroke than the other .
    I chronoed both guns and running at 800 fps with a 3-5 fps spread with aa express, as I had set them up previously.
    Swapped them over and let the cold one warm up and the warm one cool down .
    The warm one cooled down over the course of the day to +3 degrees and chronoed at 802 with the same spread .
    The cold one warmed up to +18 degrees and made 800 fps with the same spread as before .
    Not very scientific, but looks like they aren't altering power with temp change unless something drastic happens as the temp drops further , fingers crossed .
     
    andyfin, Peter Trimmer, nick2 and 2 others like this.
  2. RobF

    RobF Administrator Staff Member

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    Sounds good Nick.
     
  3. Leadedd

    Leadedd New Member

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    That's excellent results well done. How much of a weight saving over original parts and have you done any work on the transfer port?
     
  4. Nick G

    Nick G Active Member

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    Comp tubes are one piece with shorter than standard ports
     
  5. Leadedd

    Leadedd New Member

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    Oh really so you've bored round bar? Still 25mm or reduced?
     
  6. Nick G

    Nick G Active Member

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    21mm
     
  7. Leadedd

    Leadedd New Member

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    That's is radical.
     
  8. Nick G

    Nick G Active Member

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    been working on 21mm in various guises for around 5 years now , LGU & TX best at 21mm, 97 have a shorter available stroke so 22mm for those .
     
  9. mrgeoff

    mrgeoff Active Member

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    Do TXs usually shift a load then?

    Mines Maybe 5fps up now in the cold weather? Didn’t seem a lot to worry about?

    Thanks.
     
  10. Leadedd

    Leadedd New Member

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    Well I'm very impressed by your figures quoted 800 fps is a high power level and if your set up has a good degree of reliability i can see being very desirable and not just for comp shooters.
     
  11. RobF

    RobF Administrator Staff Member

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    The only problem is that sometimes you don't see the shift on the chrono. The theory is the compression on the seal occurs at a different time in the stroke and causes a POI shift because of the change in recoil.
     
  12. Nick G

    Nick G Active Member

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    800 fps with 7.9 gr , as Rob says the change in fps doesn't have to be much, it can make the poi move a lot by altering the point of pellet exit in the recoil cycle , ie because the barrel is moving when the pellet exits , it needs to exit at the same point every time for it to to be accurate .
     
    Gary Martin likes this.
  13. RobF

    RobF Administrator Staff Member

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    Yep. I want to revisit this some time. But initially every time I chrono'd the rifle when I saw shift it was within what most would say is not enough to see the shift I saw. However I've the sneaking suspicion that not chronoing at the exact time I saw the shift could also be an issue with this theory. It's not good enough to just wander off a course and chrono 10 or 20 mins later... you can see shifts sometimes that fast, or you might only be 1/2 way away from where you were. But one thing I do know is the seal has a big part to play in shift and that is the only reason I see it now. I can put my rig in and out of a stock etc and not see a click of movement.
     
  14. Adam

    Adam Well-Known Member

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    I've seen these shifts on plinking range where I've been able to put the next few shots over the Combro and they were the same within reasonable range (10 fps as I say). It's not definitive proof, i.e. I didn't capture the actual shot(s) when it shifted but the shift was for at least 20-30 shots so should be representative.
     
    RobF likes this.
  15. dave croucher

    dave croucher FT, the sport where simple becomes complicated

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    Clockwork gun shooters are weird.
     
    Andy P and RobF like this.
  16. Andy P

    Andy P Gently does it......

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    Yeah whats with the massive key.?
     
  17. madplinker

    madplinker Active Member

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    Hi
    Possibly not temp shift but anyone any idea's ???

    I was shooting my lgu on Saturday morning so was -3 or possibly -4
    Anyway I was 're zeroing the rifle due to putting on a one piece sports match mount on.
    So firing away got a zero and generally shooting away at near and far targets no problems
    At all by the end of session nearly shot around 80 pellets possibly a bit more.
    Last couple of shots missed 45 yards target when I was hitting it no problem and felt rifle had climateised
    So checked 25 yard zero pellets where going pretty much a inch low put 3 shots pretty much through same hole no left or right movement no wind as well.

    Checked the stock screws also the mount screws all nice and tight. ????
    The scope is fantastic so 100 percent nothing to do with that.
     
  18. madplinker

    madplinker Active Member

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    HFT scope never had any problems with scope its bullet proof ft scopes seem to suffer with temp shift that's why adding this part.
     
  19. RobF

    RobF Administrator Staff Member

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    Was the 25 yard target the same target as before? Did you chrono?
     
  20. steve1000

    steve1000 Active Member

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    scope and mounts bedding in possibly ?
     

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