I shot my Ruger Old Army for the first time last night. Never fired a BP gun before - bloody hell, thunder, smoke and flames or what! My problem is that the primers didn't go off half the time and I had to shoot the cylinder again. One took three goes.

I used 777 powder at 18 grains, Alox on the 457 balls and a felt wad. The caps were given to me: Number 1075 Dynamit Nobel. Is this normal or do I need different caps?