Breech plug metal?

[fix]

I have a belgian barrel that I need to proof. The wedding ring cut is too far down from the breech and the metal under it is .050" thick. I'd prefer if the cutting was closer to the breech where the metal was thicker leaving at least .070"
It's an octagon to round barrel, but you probably already figured that out. Anyway, before I start building this gun, I'd like to test that barrel to see if it's gonna be worth my time. It's a small barrel around 40 cal. and the breech plug is only 1/2 by 16 tpi. I can't find a breech plug for it, so I was thinking about making one out of a bolt. I can turn down and thread an off the shelf bolt for the breech plug, but I was wondering what kind of bolt to start with. I figure that a standard bolt would work, but I could easily find a grade five to use instead.

Any opinions.

By the way, If the barrel isn't going to work because of that cutting, I think it will still be long enough to cut into a pistol barrel, so either way, I'll need that breech plug.

Thanks

[oldiemkr]

Are you sure its 1/2 x 16 ? Never heard of that one. 1/2 x 13 or 1/2 x 20 are standard. Yuo might have metric.

I'd open it to a 9/16 breech plug if I decided to use it at all.

I'd never even consider a bolt off the shelf from a current box store or even a local hardware store. Where they came from and the quality of the metal used is real suspect. The thread quality is quite often really bad.

If its worth doin do it right.

[Acer Saccharum]

I don't understand from your description where the metal is thin.

[fix]

Found an old thread. Thanks.
I'd still take advice though.

I was more interested in the steel than the actual bolt. I'd be turning it and threading it on the lathe. Looks like i might be better off ordering some mild steel  than using a bolt.
I measured several times. The plug is 1/2 inch by 16 tpi. If it was more standard I'd be able to just buy a new one. I considered re tapping the barrel out to a bigger/more standard plug, but it's such a small barrel that I would be afraid of weakening it in a new place.

I do have an original breech plug for this barrel, but I can't very well drill a hole in it without knowing where the lock will fall. What I would like to do is install a plug just for proofing, remove that plug, and begin the build using the original plug.

This plug would be just for testing the barrel.

I'd also be more than happy to buy a plug if anyone can find a 1/2 inch 16 tpi plug out there. It'd likely be way cheaper than turning one out.

Thanks again.

[fix]

Where the metal changes from octagon to round, someone filed a ring. This is usually done farther up the barrel, where there is more metal. In this case it was done too far down, and the metal where the ring is filed is thinner than I would like. There isn't really a way to put metal back there, so I'm trying to decide if I still have a long gun barrel, or if I have a pistol barrel. Since the ring is so far down, there should be plenty of room to just cut the barrel and make a pistol with it. I would, however, prefer to build a rifle. Hence the problem.

[Acer Saccharum]

You should probably use a new barrel for a rifle, as pressures can be pretty high, especially in the breech area.

[D. Taylor Sapergia]

...especially in a small bore like a .40 calibre.