Can be done but could be DANGEROUS! Those barrels have a very unusual patent breech. Where most breechpugs screw into the barrel, those Philly Derrenger barrels screw into the plug. In other words, the breech is not a plug but a cap. If you were to run a 1/2" drill all the way to the bottom there would not be much barrel wall to hold the breech cap. I stopped my bore about 1/8" short of the front of the cap. That leaves a .45 caliber chamber about 3/4" long which will hold about 30 grains of powder. If you tried to load less than 30 grains you could not seat the ball tightly on the powder since it would stop where the drill stopped, but who wants to shoot less anyhow? :haha:
