I have a 12 gauge double barrell shotgun made by William Ketland, @ 1830. I believe it was converted from a flint lock to percussion (no. 11) a long, long time ago. I use it for re-enactments as Texas State Troops or the Confederate Bushwhacking Dept., if I am out of state. Even with these small caps there is a substantial discharge with 60 grains of powder in each barrell.