I’ve already been through that, going the other direction; group size decreased with increasing powder charge.
The charge I’m using is just under what the guys at the powder manufacturer recommended as the max safe load.
And the primers do indeed say “You’re right at the limit”.
But, it gets a 190 grain MatchKing up to roughly 2900 fps.
If you’re working your way up to a max-power load there is a test you might like to do to check how efficient your “burn” is. We use a plywood frame with a hole cut in it just slightly smaller than a sheet of white typing paper. Staple a sheet over the hole and fire thru the paper with the frame about a foot in front of the muzzle. Too close and you’ll blow away the paper unless you have a flash hider but when you find a distance that doesn’t blow the paper you’ll get a check on whether all your powder is burning. We use this test more to help check efficiency of recoil reducers but it’s also a simple check on whether you’re wasting powder.——carry on——Semper Fi