I have a 25-5 8 3/8 that has a cylinder that has been machined for ACP's in moon clips as well as the LC's. It shoots LC's well, but was key holing the ACP's. I tried some FMJ's instead of the 255gr LSWC's and 230 gr LRN I had been shooting, and the key holing stopped. I have since pin guaged the cylinder throats, and there are 5-.451's and 1-.452. It was suggested that, based on those results, I should try a very hard leads bullet of a type that gets the maximum contact with the rifling. I have been considering a LRNFP 255gr bullet for this application. What are your views? Do you have a suggestion about this approach, and/or a source for a bullet? Thanks for all contributions, Flapjack.