Breech plug thread repair

[Spyridon1219]

I made a rookie mistake and buggered up the threads on my breech plug with the vise while doing some shaping. I guess I didn't have it cushioned well enough. Is there a way I can repair the threads with a file or something,  or should I just go ahead and start over with a new breech plug? I don't want to ruin the threads in my barrel over a ten dollar breech plug.

[Acer Saccharum]

There are thread files which smooth the threads up nicely. Thread repair file: http://www.mcmaster.com/?m=true#thread-repair-files/=11c8oga

If the threads are severely damaged, get a new plug. You don't want to compromise your safety.

if the thread crests are just rounded over in a few spots, file them up true again.

[Longknife]

Just run a die, of the proper size over it. If you don't have one. they can usually be purchased at any hardware store for under 10 bucks. A small triangular file will work also, just be careful and file slowly, checking fit often......

[Mark Elliott]

I concur with the last two posts.   You don't want this to happen again though.

If you don't already have them,  cut some vise jaw liners out of 3/4" cabinet grade plywood.    The are rectangular with a slot in the middle to ride on the vise screw/cover.    They look like a 'U".  They should be a little loose so that they can rack a bit to accommodate an object that isn't quite square.   

I also usually  file the tang with the breech plug installed in the barrel most of the time.   That way you don't have to worry about messing up the threads.    I even have an old section of barrel that I use to hold breech plugs for forging the tangs to shape.   Before I ruined a barrel that I could reuse,  I drilled and tapped a section of 1 1/4" bar stock with a 5/8 thread on one end and a 3/4" thread on the other to hold breech plugs in a vise or tongs.     Just some ideas for handling breech plugs.
   

[Spyridon1219]

Thanks. I'll give the thread file a try. Hopefully it works since the breech plug is already fitted. It would be nice not to have to fit another plug and shape another tang.

[Dphariss]

Thanks. I'll give the thread file a try. Hopefully it works since the breech plug is already fitted. It would be nice not to have to fit another plug and shape another tang.

If its a 5/8 or 3/4 get a grade 8 nut of the proper size and pitch and using some STP work it down over the threads a little at a time. This should reshape the threads without any cutting unless they are really in bad shape. A nut can also be used as a thread protector.

Dan

[Joe Stein]

For future work like breech plugs and other threaded parts, get a nut that fits the part and cut a slot in the nut. Screw the nut on the part, and put the nut with the part in it in your vise with the slot up.  Tighten the vise, and the nut tightens on the breech plug or whatever part you are working on.  The part will be gripped tightly, but the threads will be protected.

[Acer Saccharum]

For future work like breech plugs and other threaded parts, get a nut that fits the part and cut a slot in the nut. Screw the nut on the part, and put the nut with the part in it in your vise with the slot up.  Tighten the vise, and the nut tightens on the breech plug or whatever part you are working on.  The part will be gripped tightly, but the threads will be protected.

Excellent idea, Joe.

[kutter]

The split nut also works well in re-shaping damaged threads.
Oil up the threads.
Then thread the plug on nearly all the way.
Then tighten in a vise to the point where it starts to take some effort to turn the plug in the split nut. You don'y have to do complete revolutions, just back and forth to re-shape the thread.
Then tighten the vise a bit more to tighten the nut around the plug threads and give it a few more twists.
Continue till you are satisfied with the results.

Always do this with oil or grease on the threads & with minimum tightening each time or you will most likely gall the threads.