Ruger replaced both cylinders (.45 ACP) and it shot much better. Each chamber is of the same dimension..as I understand it they make 'em better these days. That did help, however at X no. of paces shooting at a steel plate offhand...I can hit it with every shot with the Keith bullet and about 50% of the time with the 250 RNF. The Lee 250 RNF and 255 SWC are also very accurate in it but not the 454190. The cylinder throats are at .451"...I size the bullets to .252". I have also tried unsized bullets..makes no difference.