issue with breech plug

[bjarard]

I'm setting up the breech plug on a round barrel. It was screwed in tight so I backed it out to apply inletting color ...screwed it back in and it appeared there was no transfer. So I proceeded to remove a little of the tang that butts agains the barrel rear. Screwed it back in and it stopped...but now with a small gap where I removed some of the tang. Backed it out again and ...again...no transfer??? I would think it should act like a giant screw...once any impedence is removed it should screw all the way down upon the shoulder.

I then screwed the plug back in and ran a straight rod down the barrel till it bottomed on the plug face...then clamped into place. Removed the plug and the end of the rod is very slightly ahead of the shoulder...indicating the plug is going all the way in.

Why am I not getting any inletting transfer?? it looks like there is some inletting transfer on one of the last threads...but I thought it needs to transfer to the larger flat area at the bottom. the plug does have a slight bevel if that matters.

 

[Comfortably_Numb]

You need to file off the back side of the barrel, not the plug.

 

[bjarard]

I tried that also. Tang gap got larger.

 

[bjarard]

I think if I start filing away at the barrel end again it’s just going to in crease the tang gap more. Is it everyone’s contention that I need to do this…that this plug has not yet seated??

 

[ronaldrothb49]

When you install a breech plug you file the end of the barrel or the face of the breech plug. you also might need to slightly bevel around the end of the breech plug, Bottoming taps leave about 1 1/2 threads that are only partial threads. If you took material off the top of the tang you would have to take the same amount off the bottom part also.

 

[#blackpowderbill]

I tried that also. Tang gap got larger.

That's because the plug has bottomed out

 

[bjarard]

That's because the plug has bottomed out

So are you saying I’m good on the plug fit

 

[The Crisco Kid]

Not if you have a gap at the tang. Have you tried cleaning the shoulder in the barrel where the tang butts up against it and then put some Prussian blue on the plug. If you screw it in tight and it transfers some stain the the internal shoulder then you need to file the face of the plug or relieve the first thread or two on the plug.

 

[ronaldrothb49]

So are you saying I’m good on the plug fit

NO the tang has to hit then end of the barrel at the same time the breech plug bottoms out. You have created a lot more work that you have to do by filing on the tang

 

[bjarard]

NO the tang has to hit then end of the barrel at the same time the breech plug bottoms out. You have created a lot more work that you have to do by filing on the tang

Based on the above pics do you see black grease transferred to the shoulder. Looks like there is some on the inside.

 

[bjarard]

Thanks for everyone. So what I’m hearing is that the plug is seated but I need to file the face of the plug to bring the tang gap closed. It is a very small gap so it shouldn’t need much face removal Correct?

 

[Pete G]

Do NOT file the face of the plug! The threads are bottomed out in the hole. Either cut the threads in the barrel deeper or relieve the last threads on the plug.

 

[smo]

Been there, done that..

Ended up here.

TC Renegade with .62 GM smoothbore barrel installed.
No more gap!

 

[Sidney Smith]

Do NOT file the face of the plug! The threads are bottomed out in the hole. Either cut the threads in the barrel deeper or relieve the last threads on the plug.

BS. If there's a gap when he tightens the tang down then filing the face of the plug is going to bring the gap down. Cutting deeper threads and now you're getting into the rifled portion of the barrel. That's a stupid thing to do. File the plug face. If it gets screwed up, much easier and cheaper to buy another breech plug and start over.

 

[ronaldrothb49]

If you are using grease as an inletting black stop and Get a candle and get some Lamp Black on the face of you breech plug. Screw it in as far as you can then take it out to see if the face of the plug face is actually bottomed out. If there is no transfer from the plug face it isn't bottomed out. DON'T DO ANYTHING ELSE UNTIL YOU KNOW WHERE THE FACE OF THE BREECH PLUG IS. When you know where the face on the breech plug is then I can tell you how to proceed.

 

[bjarard]

Gap fixed. I even have contact to the shoulder( almost 360 but for a small area where the thread starts). I had to do a mix of filing the back of the barrel and plug face…wasn’t much but I think I got it. Thanks for all the advice on the matter

 

[smo]

Just be glad it wasn’t an octagon barrel…
Congrats on the fix..

 

[chorizo]

Just be glad it wasn’t an octagon barrel…
Congrats on the fix..

Cause round and round you will go!

 

[SDSmlf]

Just be glad it wasn’t an octagon barrel…
Congrats on the fix..

Actually find octagon barrels easier to install plugs. Flats provide reference points.

 

[smo]

Not when the sights have already been drilled and tapped….

We learn from our mistakes…