Breech Plug Too Short In Barrel

[EC121]

However, I was a bit surprised to see in the first video how he cold bent the tang to match the stock profile. Never having done that before, I didn't realize you could cold bend the tang like that. Bottom line, thank you for showing both videos.

Gus

Bending the tang is even easier if you make a few light hacksaw cuts under the tang and remove the radius where the tang hits the lug.

 

[W.T.]

This it?
http://americanlongrifles.org/forum/index.php?topic=10970.0

 

[Herb]

W.T., you are great! Thanks!

 

[Treestalker]

Another option is to make a plug from a bolt and weld a tang piece to it in the correct position.

Make sure your bolt has the three marks on top, this will be in the 55,000 lb/square inch, or so I'm told. Zonie can nail this for us.

 

[Treestalker]

I never heard of a threaded 5/8 x 18 hole that deep (.7812) in a barrel nor a breech plug longer than 5/8" (.625). I remember an old mountain gunsmith out here in Utah fitting a dime in front of a 3/4 x 16 plug to fill a gap. This could be done with a metal that could be filed to a disc shape just a little thicker than needed and push fit into the hole and then push-fit to the shoulder of the barrel. A metal that would not rust easily, maybe not brass or steel (too hard), perhaps German silver, copper might be OK. Could be a sandwich to get it thick enough. The breech plug turned to correct alignment would make a crush fit at the front against the shoulder. Some years ago I posted a tutorial in this Gunbuilder's Bench on how to fit Hawken breech plugs. Detailed instructions and photographs. It should still be here, but a quick search by me did not find it. Probably called "Fitting a Hawken Breech Plug" by Herb. Can someone find it?

I read somewhere that Whitworth BL cannon were fitted with a copper plate to convert them to muzzleloader if needed. So it should be a valid fix for a short plug.

 

[45man]

This is pretty much the direction I will have to take, because yes, the barrel has already been fitted to the stock, I just wish I had noticed the rather deep depth of the barrel's breech to shoulder path earlier on.

Thank you Zonie and everyone else for all your suggestions and replies.

Here are a couple of videos of a task that most builder's will run into when installing a breech plug. My problem on this particular DGW barrel is just the opposite of the plug fitting described in these videos. I really do not know why the thread depth in this barrel is so deep, but many of the suggestions here in this thread might possibly help other new builders.



Another one, check at 2:42 minutes in.

Kind of a shoemaker thing going on here. No padded vise and pliers. Those pliers would be 200 yards in the back field.

 

[Eterry]

I cringed everytime he chucked it up in the vise...it may have been a slick jawed vise, but would still leave marks. When he broke out the channel locks i thought he was gonna unscrew a p trap on a drain....but at least he didn't use a pipe wrench.

 

[Zonie]

Make sure your bolt has the three marks on top, this will be in the 55,000 lb/square inch, or so I'm told. Zonie can nail this for us.

Three radial marks on the bolt head indicates it's tensile strength if between 74,000 and 85,000 psi.

As most muzzleloading barrels are made from steel with a tensile strength around 57,000 psi, using a bolt material that is much stronger really doesn't have much value. A steel bolt without a head marking would have a similar 57,000 psi strength with the barrel.

Of course, using a higher strength bolt wouldn't hurt anything.

 

[Col. Batguano]

You're going to want a shorter plug than 5/8" anyway. That length of plug is going to force the lock pan pretty far forward, especially if you plan on using a TH liner. That of course will affect the trigger, trigger guard, and the rest of the gun's architecture. If a straight hole you can get it a bit closer to the plug face.

Don't think 1/8" means that much? Look at a gun with a 1/16" web at the breech and then look at one with a 3/16" web. The difference is night and day.

You didn't say what caliber it was, but more than 8 thread engagements is unnecessary for strength, especially in a coarse thread like 18 TPI. If you look at older guns, often the plug length was roughly equal to the bore diameter.

 

[Treestalker]

Three radial marks on the bolt head indicates it's tensile strength if between 74,000 and 85,000 psi.

As most muzzleloading barrels are made from steel with a tensile strength around 57,000 psi, using a bolt material that is much stronger really doesn't have much value. A steel bolt without a head marking would have a similar 57,000 psi strength with the barrel.

Of course, using a higher strength bolt wouldn't hurt anything.

Thanks, Zonie.