I have had a Blackhawk 45 colt/45 acp convertible since 1978. I have shot 1000's of loads approaching 44 magnum pressures-velocities with no ill effects whatsoever! Just as tight as the day I acquired it. I wont list my loads but they were taken from an article in a late 70's vintage Shooting Times. I backed off some from the published maximum loads. Excellent accuracy with cast bullets too.