With both guns I was maybe 2-3 cylinders in. My load was 24 grains of goex fffg, felt wad, grease over the chamber mouths, and a remington #10 cap. I was using 451s for the both guns and both shaved a ring of lead when seated. Caps were tight. Both guns almost new, very tight, no cylinder end shake. On the remington, the chamber to the left of the firing chamber went off. For the colt, it was on the right side, and happened on the first shot. The second on the remington fired directly into the rammer, but didn't cause damage.