I have used black powder in 45 colt, 357, and 44-40 rifles, I got the least amount of blow by from the 44-40. I tried annealing the 38, and 45 brass but still got blow by which dirtys up the action then they get hard to work. The thin neck of the 44-40 expands well and seals the chamber from blow by. My normal clean up on my 44-40s is open action, put funnel in barrel, pour hot water down, then run a Murphys oil rag down the barrel(50% Murphy oil 50%rubbing achahol), oil outside and done. Takes about 5 mins. 38s, and 45s I needed to disassemble the action.