Originally Posted by skires
This poi shift isn't like that. It's virtually all pellets in a very good group on zero ... then the poi moves vertically by 20mm or so. I reclick the scope ( I think it can be as much as 20 clicks or so [ 9x ] ) to rezero and all my aim points are bang on again and the groups are excellent.
That's it in a nutshell.
Now the only thing i'd say to muddy the water is that when shooting a pcp, and it comes off reg, you can hear the muzzle report change pitch, you know it's coming off reg, and there's no surprise to see pellets going south, yet the chrono will show very little difference at first. That's really muddying the water though, and over the chrono i saw no correlating shift between numbers and POI.
Here's a story... all of these will be a minimum of 5 shots, off the knee, indoors at 25yds and besides me cocking, i'm not moving position.
Happy with that
Then we will go for a wander (this could be 30 mins into a session or 3) There vertical groups are me trying to catch up, shooting pellet at the last pellet until it stops climbing (in this case, sometimes it drops).
Then we'll stop wandering (note there's one shot low and the rest are level... that's me clicking too much now she's stopped)
Then we'll stay where we are again.
Any if i move the turret for the new shift back to zero, all my numbers will be on song.
That's a smaller one by the way, i've been 20mm+ out at 25yds. And like Skires, i've fastidiously measured everything, and we've dont a lot of work to the stock to ensure a silk glove fit. She doesn't even touch wood anymore with phil's pillar bedding (which is set up using a circuit tester to ensure minimum but positive contact).
For me there's no change recoil between a high or low shot, nothing logical on the chrono. It's always vertical. It does it in constant or changing conditions. It will hold for 20 shots, or 200. It will always group well. In fact my 97 eats bad batches for breakfast... those groups were all done with a batch i can't get anything like with any of my pcp's.
Dunno. I'm going with the compression chamber not having any slack in it... but i've got some new bits coming to rule out the piston itself.