My POI is Walking!?
A little while ago, I spent a lot of time (and pellets) with the crony adjusting my rig wich is a .22 condor, 24″ barrel, removed hammer weight, with a standard talon valve.
I adjusted the top hat, my PW and fill preasure, so that using kodiaks and filling at 2650psi, i get 30 shots at 40FPE avg (thats about 930fps), with an extreme spread of less than 50fps from shot 1 to shot 30.
The thing is, last saturday i did a lot of testing shooting paper at 45 yards, and i noticed that my POI slowly “walks” from right to left for about 1.5″ total.
I can reliably repeat this all the time, first shots after a refill are little less that 1″ to the right, and then they begin to walk to the center, then past it, and last shots are a bit to the left.
I know its not the scope or the way im holding the rifle, because this happens EXACLY the same way every time i fill the rifle.
I also checked the screws on the TH, the ones on the barrel, etc. everything is snug & tight.
i also ruled out velocity change issues since the crony sais its variation is less that 50fps thru all the charge, so..
im clueless as to why is this is happening. 🙄
any ideas?
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I’ve never heard that one before. Odd!
Mike
Heres what i did…
I opened my TH by about 1/4 of a full turn, wich increased the gap a little.
I will do some more testing next saturady, and ill let you guys know how it went.
thanks
Maybe time for a custom tophat to give you more clearance in the back.
i remember someone mentioned a while ago that if the tophat is slaming against the valve face, your POI would change.
My tophat is in fact pretty close to the valve face, maybe this is the problem?
If it is, then i have another problem 🙄 if i open my tophat to avoid this, then my shot count will decrease.
i dunno what to do 🙁
I see what you mean. I am getting it with a 200+ fps drop. Not 50 fps. 😕
hey, thanks for your reply.
Yes, the velocity/spin issue makes sense, but ¿can it be so dramatic (almost 2″ @ 45yrds), for a speed variaton of less than 50fps? Total ES thru all the charge is about 46fps.
I tought i would see that with speed variations of say 100 – 200fps. ¿but for only 46fps?
My .25 walks left and low as the velocity decreases. My guess is that it is a relation between the spin imparted by the rifling twist in relation to the velocity. Just one more reason I am looking at a Reg’ed rifle or at least one with a much more uniform shot to shot spread.
Mine does just fine for the first 30 shots, then it starts the walk and drop. I don’t mind the drop, but the right to left walk isn’t acceptable.
Mike
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Mike
About the POI shift when the tophat slams the valve face?
I think it was WOK or YN that mentioned.
was it you Adam?