CURX vs RWS in CZ 457

[stagpanther]

This is my CZ 457 on 32 gr CURX at 70 yds:

This is my CZ 457 on RWS R 50 at 70 yds:

any questions?

 

[hounddawg]

what I do is shoot 5 groups of 5 shots each and average them

 

[stagpanther]

I have a strong suspicion that the CU solids need a particular bore and rifling cut to truly tap their potential.

 

[stagpanther]

The problem as I see it is this: a conventional 1:16 twist 22lr rifle's bore is going to be optimized for impressing soft lead into the grooves and bore. The CURX is narrower and has only the drive band to engage the rifling, which it barely engages on my CZ 457 as far as I can tell. I may be totally wrong and it's pure speculation on my part--but I think the CURX is rattling down the bore off center in my CZ, which is otherwise superbly accurate with conventional subsonic cast ammunition. I think all I'm doing is prematurely wearing the bore by firing the solids in it. I just got back from trying out one of cu's top loads for the 32 gr bullet--only in the fastest compressed loads could I keep the groups within minute of barn door but well in excess of 3 MOA. Just as a reality check, I shot a quick string of R 50's off the hood of my truck @ 117 yds--were it not for the top flyer this would have been well under MOA.