Damaged breech plug

[RG96]

I just got a second hand parts kit and the breech plug had some damage to the threads. I had to file off the bottom thread or two. Is there any reason I shouldn’t use it?

 

[SDSmlf]

Was the breech plug previously installed in the barrel?

 

[RG96]

No, it’s a green mountain

 

[Jaeger]

My opinion: no problem.

 

[Flintandsteel]

You’ll probably file all that off to fit your barrel, and then some.

 

[SDSmlf]

No, it’s a green mountain

I would remove that area where you filed off the threads, maybe .012” to square the plug up and then proceed with installing the plug. The slightly shorter threaded plug won’t hurt anything. You will wind up taking it off the barrel, depending on the depth of the threads down to the shoulder in the bore.

 

[RG96]

The plug and the threaded section are both 5/8. If I shorten the plug I have to take the same amount out of the barrel right?

 

[nhmoose]

No!! the front of the plug should contact the full circle of the front of the breech threads. There are plenty of threads on the plug for safety.

IMHO a die should have been used to fix the threads in the first place.

 

[SDSmlf]

No!! the front of the plug should contact the full circle of the front of the breech threads. There are plenty of threads on the plug for safety.

IMHO a die should have been used to fix the threads in the first place.

He’s already basically removed the threads from the plug about an 1/8” back with a file. How does he make this work without removing that material with no threads from the front of the plug?

 

[Shooter1]

Bore should be smaller than plug, so breech plug should be left full length to bottom against barrel.

 

[SDSmlf]

Bore should be smaller than plug, so breech plug should be left full length to bottom against barrel.

True, could work if bore is smaller that what the nose of the plug has been cut down to. I just don’t like that empty area with no thread engagement, kind of creates an unnecessary manure trap. Just not an area in my opinion to take shortcuts.

What is the caliber and the plug thread diameter?

 

[RG96]

It’s a 54. Caliber with 5/8-18 thread

True, could work if bore is smaller that what the nose of the plug has been cut down to. I just don’t like that empty area with no thread engagement, kind of creates an unnecessary manure trap. Just not an area in my opinion to take shortcuts.

What is the caliber and the plug thread diameter?

its a 54. Caliber with a 5/8-18 thread

 

[Zonie]

Removing the first thread or two won't hurt the breech plug at all. In fact, doing this is my recommended way of solving the problem of the breech threads not being full threads all the way to the shoulder that the breech plug bumps up against.
It is a lot less expensive than buying a special bottoming tap and it eliminates the need to have one.

Just be sure that when you remove the threads, you don't reduce the existing diameter where the root of the thread was. As long as that root diameter is left alone, the face of the breech plug will seal off the bore nicely.

 

[nhmoose]

Removing the first thread or two won't hurt the breech plug at all. In fact, doing this is my recommended way of solving the problem of the breech threads not being full threads all the way to the shoulder that the breech plug bumps up against.
It is a lot less expensive than buying a special bottoming tap and it eliminates the need to have one.

Just be sure that when you remove the threads, you don't reduce the existing diameter where the root of the thread was. As long as that root diameter is left alone, the face of the breech plug will seal off the bore nicely.

Well stated Zonie!

That is how I always make a breech plug.

 

[Flintandsteel]

What Zonie said. Every one I’ve ever fitted looked pretty much like yours when it’s done. The threads in the barrel are never full depth at the bore.

 

[toot]

I would say that you still have plenty of threads left on the plug.

 

[Eric Krewson]

I shortened the plug and breech of the last GM barrel I breeched so the snail of the lock lined up with the end of the barrel. I still had a little over 1/2" of threads in the breech. I couldn't get threads to the bottom of the breech even with a homemade bottoming tap. I filed off the first thread or two to get a good seal, just like your plug.

It ended up like this;

 

[jager43478]

The plug and the threaded section are both 5/8. If I shorten the plug I have to take the same amount out of the barrel right?

Put some kind of coloring on the face of the plug then thread into the barrel. Then remove to see if is hitting the shoulder of the inside of the barrel (rifling portion) if so go with it.

 

[RG96]

Cool thanks everyone! This is my first build and my first flintlock. Lol I might be in a little over my head

 

[jager43478]

Just take your time , walk away if things get frustrating.