Breech Plug Too Short In Barrel

[Cpl. Ashencheeks]

I have an old Dixie Gun Works 15/16" straight octagon barrel with 5/8" 18 TPI Thread pattern.

The problem is while the breech plug fits the barrel threads fine with no shake from side to side, it falls short of the internal shoulder.

The length of the plug to from the face of the threaded plug to the front edge of the tang portion is .5781" with the depth of back end of threaded barrel being .7812" to the internal shoulder.

This means the plug in the barrel leaves about .2031" of exposed threads within the barrel, which I assume can be a fairly serious safety hazard.

What can I do to possibly remedy this problem?

Should I (a) order a new breech plug and hope for the best regarding the thread length of the plug in being long enough to jut up against the internal shoulder or (b) should I get a machined plug blank and use the appropriate die to cut the threads?

If I do the later I would still have to be concerned about the plug length being long enough to reach the internal shoulder.

Has anyone here ever dealt with this kind of problem and if so how did you go about solving it?

Thanks in advance for any replies.

 

[bubba.50]

Or you could chuck the barrel in a lathe & trim about .2031 off the rear end.

 

[SDSmlf]

Or you could chuck the barrel in a lathe & trim about .2031 off the rear end.

Don’t see how that helps. Based on thread pitch (18 per inch) trimming .2031 off the rear of the barrel results in 3.66 turns. Flats and sights dovetails no longer line up with the breech plug or have I missed something?

 

[bubba.50]

When ya get’em the same length, if the flats/dovetails don’t line up, hit the front of the plug & the back of the barrel a few file strokes. Continue ‘til everything lines up like it’s ‘sposed to. Easier than it sounds just takes a while sometimes.

 

[Cpl. Ashencheeks]

Don’t see how that helps. Based on thread pitch (18 per inch) trimming .2031 off the rear of the barrel results in 3.66 turns. Flats and sights dovetails no longer line up with the breech plug or have I missed something?

The barrel has not yet been dovetailed for sights but there are hammer pinned lugs at the bottom flat which would be where the center writing stamps are. Three of the flats on the have writing being Dixie Gun Works Inc. on the bottom flat with caliber and powder type warning and Italian proofing stamps on the other flats on each side to DGW stamp.

I might also consider drilling tapping the center of the plug and adding an appropriate length of cylindrical metal to be threaded with the proper die.

Any way I look at this it does not seem that solutions will be easy unless I get the correct length plug in replacement.

 

[EC121]

After machining, you will have to fit the plug to line up with the proper flat and breech face at the same time. Not a big deal. Best to leave the plug a little long. Then just file and try til it fits. It can be tedious, but it can be done. The plugs are never correct length. They can be close, but still need a bit of fitting. Some one, either at the factory or at home, has to fit them. Even Rice barrels come with layout blue on the plug face where they have been fitted. They just don't have to be timed to fit a certain flat, and can land wherever the plug fits.
Track of the Wolf and probably others will fit the plug for you, but labor, parts, and postage could add up.

 

[bubba.50]

The barrel has not yet been dovetailed for sights but there are hammer pinned lugs at the bottom flat which would be where the center writing stamps are. Three of the flats on the have writing being Dixie Gun Works Inc. on the bottom flat with caliber and powder type warning and Italian proofing stamps on the other flats on each side to DGW stamp.

I might also consider drilling tapping the center of the plug and adding an appropriate length of cylindrical metal to be threaded with the proper die.

Any way I look at this it does not seem that solutions will be easy unless I get the correct length plug in replacement.

Even if you get ‘the correct length plug’ there’s a more likely than not chance the flats still won’t index correctly and you’ll end up needin’ to tinker with it to get everything to line up anyway.

 

[Pete G]

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

 

[Zonie]

I suggest giving Track of the Wolf a call @ 1-612-424-2500 and telling them about your breech plug.

Tell them you need a 5/8-18 threaded plug for whatever your barrel octagon size is and it must be 5/8" long on the threaded end.

Based on the photos they show in their catalog, they have just what you need.

Of course, you will need to do the filing on the plug and probably on the end of the barrel to get the new plug tang to end up in the right place but that's just the nature of the thing.

 

[Eterry]

Cpl., if you stated whether the barrel is mounted in a stock i missed it.

If it isn't stocked yet you can put it in a vise and CAREFULLY file away the excess material AND get the tang properly timed.

There HAS to be a video on YouTube of someone doing the same. A lathe is handy, but not necessary.

I was just as surprised when i ordered my 40 cal barrel and tang from TOTW. i don't think mine was off 20 thousandths, but it was off and had to be timed so the tang mated up to the bbl correctly.
Good luck.

 

[rich pierce]

This is just normal business. Folks, the plug was not likely timed anyway.

When scratch building, the builder makes decisions and makes the parts fit their design. For example decide you want a half inch of threads and cut barrel and plug accordingly.

 

[Sidney Smith]

You have plenty of length on the barrel to play with. Cut off 1/8th inch then start filing the back of the barrel. Test the plug out every so often until it fits tight to the flat or your choosing as the top flat. Since you said you don't have dovetails cut yet for the sights its a fairly easy fix.

 

[Flintandsteel]

If the barrel is in a stock, you would cause more trouble for yourself.
Zonie has the right idea, new breech plug. Fit the plug to the barrel, then the barrel stays the same length, and your pin holes still line up.
If just a barrel, file the breech of the barrel.

 

[Cpl. Ashencheeks]

If the barrel is in a stock, you would cause more trouble for yourself.
Zonie has the right idea, new breech plug. Fit the plug to the barrel, then the barrel stays the same length, and your pin holes still line up.
If just a barrel, file the breech of the barrel.

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.

 

[bang]

Ok just asking for curiosity. In this instance. If the plug when tight lines up could an outside threaded spacer be inserted ahead of the plug to fill the gap?

 

[Cpl. Ashencheeks]

Ok just asking for curiosity. In this instance. If the plug when tight lines up could an outside threaded spacer be inserted ahead of the plug to fill the gap?

I had considered that as one option, but it could present an extra space for black powder residue to deposit into and give extra potential for corrosion of the threads weakening the strength of the breech area.

There is some argument that the breech seals at the face upon the shoulder and others argue that breech seals at the thread. I think I would prefer it seal at the face of the shoulder which would make a threaded spacer more viable, but it is still safer to have a long enough plug.

I have a question for any machinists watching this thread. Is the term 'Journal Length' meant to mean the length of the threads or the overall length of the cylindrical area of the plug?

 

[bang]

I had considered that as one option, but it could present an extra space for black powder residue to deposit into and give extra potential for corrosion of the threads weakening the strength of the breech area.

There is some argument that the breech seals at the face upon the shoulder and others argue that breech seals at the thread. I think I would prefer it seal at the face of the shoulder which would make a threaded spacer more viable, but it is still safer to have a long enough plug.

I have a question for any machinists watching this thread. Is the term 'Journal Length' meant to mean the length of the threads or the overall length of the cylindrical area of the plug?

Agreed, a proper length plug is best. I can understand the possible need to fine trim barrel for clocking but even that does not seem to insure that the plug would be 100% upto the end of the threads. Seems it would be better fit to have the plug slightly longer then trim the plug to clocked. Only way I can see insuring the plug threads reach the end of the travel. However for complete seal the flange of the plug has to meet just prior to clocked then the torque will pull tight in threads and at flange. I ask because I recently pulled the breach plug from 2 barrels. From looking at them neither of the threaded portions actually reach the complete reach of their threads in the barrel. Close but not all but for sure not 0.2" short. This is why I'm thinking touch at flange and torquing seals both flange and threads with minor gap. Does that sound right?

 

[Artificer]

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.

I like the second video much better because it shows fitting the breech plug face against the internal shoulder in the barrel. I'm not sure if that was done at all in the first video. I think other members have mentioned how in the period they sometimes used a lead or copper ring spacer when the plug face wasn't long enough to fit up against the internal shoulder?

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

 

[45man]

I never had that much to fill and a longer plug is best to use more threads. I use a brass spacer to seal the inner shoulder and is easier to fit to line up flats. It is really hard to seal and line up flats with just the plug.

 

[Herb]

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?