Avoiding POI shift due to Tophat slam
I have confirmed what ibe read here, that when your TH is too close to the valve head, your POI starts to move to the left once the presure gets low enough.
My setup is a .22 condor, 24″ barrel, with hammer weight removed, and a standard talon tank (and valve). My TH opening is 0.078″ and my PW lives at 6 (it seems to be more consistent at this setting).
My question is, ¿what is the minimum TH opening i should have, to keep the tophat from slaming into the valve at lower presures?
On a side note, i dont have a crony to verify this, but it seems the power weel has no efect whatsoever on velocity. from judging pellet drop at 80 meters, it seems to shoot at the same velocity with PW at 0 that with PW at 12.
And on another side note, i guess my valve is “unusual” because i cannot close the TH much more that its current setting (0.078″), i can open it of course, but if i try to close it more, it just wont turn anymore.
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Oky doky…..No more worries….
Just like get the BJ said, only worry about pulling the breech against the tophat fully.
Dont worry about the frame
the play is of no concern, just pull the breech against the top hat and shoot.
Oh yea…..0.10…..Thanks for straightening me out….So my TH is 0.10 with about 0.039 slack between breech and TH when cocked…You can see by teh TH set screw that the breech does not fit tight against the TH…Hopefully the pictures will explain….
Breech pulled all the way back
Breech locked and pushed forward…
.010 wouldn’t even shoot.
0.010 as in 10/100″ ? you mean 0.10 like 1/10″ right ???
I don’t know, personally though I don’t think .040 would be reccommended.
Something strange here, usually the tophats are between .060 and .092″ so I would check the gauge and make sure you are measuring from the brass surface to the tophat any chance you can post a picture of your tank?
Randy
I have about .0024 and don’t know any other way to tighten that up….
None at all.
Randyhub, when you cock your gun is there any space/slack between the breech and tophat once you lay the breech knob over?
My tophat is happy at .062.
Randy
knifemaker, I had so much slack between the TH and the Breech that the breech knob was banging up the frame. So I moved the TH to 0.010 to take up some of the slack….
.010 ??? 😯
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Strange,
that problem about POI shift to the left (presumably) due to tophat slam,
ITS GONE!
I dint do anything to the gun, and on saturday i went shooting, set up a paper target at 85yards, filled to 3000psi, and shoot for about 65 times, till my presure was only 1700psi.
I did notice POI change in the last shots, but it was only vertical (shots goin lower) wich is of course normal. But no POI shift to the left (or right) whatsoever.
I repeated the experiment a couple of times (i am now officially out of kodiaks 🙁 ) and got the same results. No horizontal POI change.
So at least for now, the problem is gone.
any ideas of what could have caused it to appear (and disapear)?