I have a Cooper Classic with aftermarket BBL. Didn't like the 14"twist factory BBL it came with. Why wouldn't shoot any thing over 52 grs very good. So I had a Mike Rock Rock Creek BBLs put install one of his Cut Rifles 8" twist BBL. So as long as I seat 75 gr A-Max into lands and fuel it with H4350 I get under 1/4" groups.About 3.400 FPS. But if I try 52 gr bullets target looks like a shot gun pattern. Today I was shooting 39.5 grs of IMR 4064 behind a Speer 52 gr HP. I'm wondering if the bullets blew apart before hitting the target? I shot that same load with Hornady A-Maxs( 52 grs they Chrony at 4,100 FPS and target look like a Buck Shot pattern at 100 yds. What should I do? I'm thinking I'lll just shoot the 75s for the life of the gun. To heck with the little bullets.
