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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I checked my FPS yesterday with an F1 chrony and with the PW at 12 it is running 835 ish and at 0 it is running in the mid 400’s so the PW can make a huge difference…My tophat is at 0.010,,,,, PW on 8 = 815
My PW does lower the velocity when at 0-3 and increase a bit at 4. But the velocity is not consistent.
Consistency on my set up starts at 6 and I leave it between 6 and 7.
On my TSS 12″ the sweet spot was 3-11
Nope, i just checked the front of the valve body, and i see no marks whatsoever.
Sounds like you have run out of threads…
Is the tophat making a mark on the valve body?
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Yes, but can you mantain that velocity thru all the shot string?
E.G. set PW at 0, fill to usual presure, and shoot till time to refill sustaining that mid 400s velocity?
Or does it shoot at 400 for a few shots , then when presure goes to say 2400psi, velocity goes up to 835?
The AF guns ibe seen behave this way. When at max presure, PW does work, but when presure drops, then it becomes useless. They cannot sustain the same low velocity thru all their usefull charge.
To me this is no big deal really, i just accept the fact that i do — NOT — have an “adjustable power” rifle. And i just shoot at the same (high) velocity all the time. And it works fine like that, i dint buy a PCP for shooting at 650fps anyway, i have a Gamo CFX for that.
It would be nice if AF dint try to sell me an “Adjustable power” rifle tho. Because, it is NOT
But NE way, i dint start this post to bitch about AF (like i usually do 🙂 ).
About the tophat slaming on the valve, i see no marks on the valve,
does it mean that the TH is not really slaming into it?