Drum fit to barrel

[Staggerwing]

Not sure if this is the right forum to post this or in the gun builder section but I figure one of you can help me with this question. I'm on my first build. I drilled and tapped my barrel and when I was threading in the drum I noticed something for the first time. There is a chamfer above the threads on the drum. So, my question is, do I need to chamfer the hole in the barrel such that the wall of the drum is tight against the barrel or can it stand off a bit as long as it's tight? I have a feeling I know what the answer is but wanted to check with you all.

 

[rawhide]

I'm not 100% shure but I want to say yes. as you couls get gases leaking there. but I would ask some one how knows more on this.

 

[Staggerwing]

Yeah, it stands to reason. This drum already has a nipple installed so I'm wondering what, if any tricks there are to getting it tight AND lined up with the hammer. The books I've read suggest it's better to install a drum without a hole for the nipple and drill it in the proper location with the hammer.

 

[CoyoteJoe]

The shoulder of the drum needs to be tight against the flat of the barrel. Mass produced nipple drums do sacrifice the last thread or thread and a half by stopping short of the shoulder. They also are very soft steel and easy to strip the threads if you put too much torque on them or even twist off if the threads have a good bite. How to best go about it depends on the size and thread pitch of the drum and the thickness of the barrel wall the drum threads into. I hate to lose that last thread if I only have three threads in the barrel wall. I have sometimes hand filed the last thread up closer to the shoulder to get just a bit more thread engagement. A better solution is a custom made drum but I don't know where you could get one made.

 

[zaxx]

I've not built a lot of muzzle loaders, but my last two both used powder drums and from my experience they can be a real hair-ball.

I would suggest that you stop where you are and get an unfinished drum with out the pre-installed nipple but threaded to match your barrel. TOTW should have them and the kit to drill and tap the nipple location once the drum is in place. This drum will be ringed to locate a cut-off and will include additional notes for installation.

The drum should draw up and fit snug - absolutely perpendicular and the inside base of the drum above the threads should take a purchase on the barrel flat. When located, the lockplate should be fit to the drum so that the two parts mate. The drum needs the support of the lockplate to endure all the hammering it's about to receive.

One last point, the threads of the drum should be dressed off flush with the inside of the chamber wall.

You may already know all of this and I don't want to insult your intelligence but I hope this will be helpful.

 

[Staggerwing]

Thanks for the advice. I appreciate it. Yes, I knew I'd have to cut the threads off flush with the inner wall of the barrel. I'm more of a woodworker than a machinist so I want to make sure I'm doing this correctly.