I have double charged at leasttwice with inlines. May have done it one other time as the recoil was horrendous.Both times Itook the breech plug out, removed the pellets and put in 50 grains of granular Pyrodex, put the plug back in, primed and fired it.It goes off with asubduedcrackand everything comes out the muzzle. The second charge did not light off either time. Once I put two holes in my 50 yard target.