You'll have to have a 250 to 260 gr CAST bullet. The powder is 296 or H110, and you can't get enough into the case to cause a pressure problem. Start with the case not quite full and work up till the gun feeds and cycles 100%. I used a compressed load with the 260 gr LFN, which givies more powder space than any 45 bullet I know of, which is important. The powder will not burn completely, so these loads dirty the gun quite fast, but it isn't intended to be a shoot a lot play load. I worked it up to make a safe magnum out of the ACP, for serious defense work, and it does that.