Author Topic: lose breech plug (Read 4470 times)

curly · « **on:** November 24, 2018, 12:24:43 PM »

I have a build that I'm working on right now with a lose breech plug. I can turn the plug almost half way, finger tight, to the next flat now that I've proof tested the barrel. The touch hole and under lugs have already been installed. Whats the proper way to correct this problem? I've already considered cutting off the tang and welding it to the correct flat. I need your advice. Thanks

Curly

smallpatch · « **Reply #1 on:** November 24, 2018, 03:06:09 PM »

Curly,
At this point, I'd say a new breech plug would be in order. Then your only goal would be getting that thing timed by ONLY making changes to the plug.
If the tang is also inletted, you'll have to deal with that as well.
I can't imagine how the fit could have changed that much via proof testing. If it was tight before, it should be tight now.
DO NOT, weld the tang to the barrel flat. You may want to remove that plug some day.

curly · « **Reply #2 on:** November 24, 2018, 04:55:53 PM »

Thanks for the reply Dane. The plug must have been louse from the beginning Dane. When I removed it, it had some kind of compound on it, like pipe dope. So whoever installed it at the factory knew it was louse to start with. I wasn't going to weld the plug to the barrel.
I was going to tighten the plug and cut the tang from the plug and reset it to the proper flat.

Curly

Mike Brooks · « **Reply #3 on:** November 24, 2018, 04:59:08 PM »

Weld a little material to the breech plug face then dress it back till it fits.

t.caster · « **Reply #4 on:** November 24, 2018, 06:16:39 PM »

Yes, do what Mike just said! It won't take much at all since you are only off by one flat (about .008" on the breech face).

smallpatch · « **Reply #5 on:** November 24, 2018, 06:27:22 PM »

Mike,
Why didn't I think of that.
That's why you make the big bucks.

Mike Brooks · « **Reply #6 on:** November 24, 2018, 06:40:13 PM »

Quote from: smallpatch on November 24, 2018, 06:27:22 PM

Mike,
Why didn't I think of that.
That's why you make the big bucks.

Big bucks....right......

Dennis Glazener · « **Reply #7 on:** November 24, 2018, 07:03:29 PM »

I guess I am dense but how does that work? I would think the weld on the face would create a gap between the tang and the barrel. What am I missing? I would think you need to take some off the barrel face until the tang clocks properly on the top barrel flat? If the plug bottoms out in the process material needs to be removed from the face.

Dennis

Dean2 · « **Reply #8 on:** November 24, 2018, 07:23:35 PM »

Personally I would look at timing that loose plug just like you do a Brake. Lathe cut a little more thread onto the plug so that it goes tight at the next flat. That will be a whole bunch easier to get a tight fit on that dressing down a weld on the face.

Mike Brooks · « **Reply #9 on:** November 24, 2018, 07:31:07 PM »

Quote from: Dennis Glazener on November 24, 2018, 07:03:29 PM

I guess I am dense but how does that work? I would think the weld on the face would create a gap between the tang and the barrel. What am I missing? I would think you need to take some off the barrel face until the tang clocks properly on the top barrel flat? If the plug bottoms out in the process material needs to be removed from the face.

Dennis

You're right, probably have to add a bit of material on the tang face as well, or peen it and dress it down with a file. He already has his lugs and touch hole in so not many options. Ravenshire used to file his plugs so they were finger tight....I might try a wrap of plumber's tape before I got to crazy.

curly · « **Reply #10 on:** November 24, 2018, 07:36:47 PM »

I can't take it to the next flat because I've already installed the vent and lugs.
Curly

D. Taylor Sapergia · « **Reply #11 on:** November 24, 2018, 07:45:23 PM »

I'd buy or make a new plug.

davec2 · « **Reply #12 on:** November 24, 2018, 07:46:30 PM »

Locktite ( Threadlocker Blue 242). Removable with hand tools, protects and seals the threads. Will fix the position of the plug until you put a wrench to it if you ever need to remove it. Easily replaced if you do need to remove the plug

longcruise · « **Reply #13 on:** November 24, 2018, 09:38:16 PM »

Seems like a New plug would be a good option.

Scota4570 · « **Reply #14 on:** November 24, 2018, 11:42:42 PM »

Is a brass washer made of shim stock ever acceptable? If the plug face is flat a disk might be used?

At 16TPI, one flat of rotation is .007"

Hlbly · « **Reply #15 on:** November 24, 2018, 11:49:27 PM »

I would want to know why proofing the barrel loosened the plug.

EC121 · « **Reply #16 on:** November 25, 2018, 04:34:41 AM »

That was my first thought. Why did the plug set back that far?

Gaeckle · « **Reply #17 on:** November 25, 2018, 06:35:14 AM »

Quote from: curly on November 24, 2018, 07:36:47 PM

I can't take it to the next flat because I've already installed the vent and lugs.
Curly

Need to do file work, like Dennis said, file some off the barrel face, then some off the breach plug face until you can clock the plug into the correct position and hopefully it will be tight. If you buy a new breach plug there is no guarantee that the new plug will line up on the intended flat and it may just clock up on a different flat altogether and at that point you will need to do file work.

mtlonghunter · « **Reply #18 on:** November 25, 2018, 07:24:33 AM »

A new breech plug from track of the wolf should be long enough to cut and file to fit up to the proper flat. The one I just got had 5/8 of thread. Most barrels are only threaded with 1/2 inch of thread. I would not bother with any other method but a new plug. If you have never breeched a barrel , there are lots of people here to assist you in doing it correctly.

bob in the woods · « **Reply #19 on:** November 25, 2018, 04:14:30 PM »

My take on this, for what it's worth. If you can turn the plug past the desired flat, then that means that the face of the plug isn't seated and, you must also have at least a bit of space between the tang face and the barrel , or else it wouldn't turn . Rather than messing with things, it would be easier to just buy another plug and file it up to fit. $ 10.00+ and some file work gets you there. You've got the old plug as a guide, so it shouldn't take too long. Or.....you can do as Mike Brooks suggested. If you end up with a slight gap between the barrel and the tang, you can peen it closed ...or, I've seen a couple filled with silver or brass .

tiswell · « **Reply #20 on:** November 25, 2018, 04:57:20 PM »

What is the caliber, weight of the barrel, what was the proof load?

I feel like I would have to at least have a conversation with the manufacturer about this before moving forward with this barrel. Did the threaded area adjacent to the bore swell slightly upon proofing? Were the internal and external threads initially made with such a large variation in pitch diameters that the threads "upset" upon firing? Did they knowingly use the pipe dope to try take up the slop? I don't want to be an alarmist, but I would want to know the cause before moving forward with the repair.

Scota4570 · « **Reply #21 on:** November 25, 2018, 06:59:11 PM »

When fitting the new plug be sure to run a bottoming tap in the barrel. When fitting the new plug it is unavoidable to taper the threads a bit in the nose of the plug as indicated by the spotting stuff.

Could it be that it was not done right the first time and it was drawn up tight on the end of the threads and not the shoulder? That will give the pressure more area to act upon and will stress the plug more. Like how a Colt Ace 22 conversion works.

Later I had another thought. If the plug was insufficiently torqued to iron out minor irregularities in the threads it would iron them out when fired.

I use a stout vice and fitted steel blocks on the barrel when fitting a plug. I lube the plug with moly paste and lanolin to prevent galling. I use a significant wrench. I work it and out several times before making a call on how it indexes. If I get a hint of galling I stop and take it out and do more fitting.

Dave B · « **Reply #22 on:** November 25, 2018, 10:45:41 PM »

Does the current breach plug face show signs that it has been modified previously or is it as stock? If it was modified you may just get a new plug and your good to go fitting it fresh. Just buying a new plug may not solve the issue if the original hole was too deep to start, now you have two breach plugs that don't fit. I had checked the breach on a new barrel before doing any thing to the barrel to make sure it was on the face of the plug and it didn't show any transfer compound on the inner face where it was indexed. I had to shorten the breach end to get full face engagement with the tang now at 180 degree from its original index point.

I think the easiest fix is to remove a little from the plug face and the tang face till you have it back to the correct index point then stretch the back of the tang to fill in the slight gap that moving the plug forward has left. This way you are not shortening the barrel from the breach if you have it inlet, barrel pined and lock lined up on the touch hole perfectly.

G_T · « **Reply #23 on:** November 26, 2018, 02:09:37 AM »

My advice here is worth nothing, but I'd probably be working in paranoid mode at this point. I'd consider it a failed proof test, and then work to figure exactly what failed and how. If the manufacturer breeched the barrel, I'd be talking with them and not necessarily being completely polite about it. If you bought the barrel second hand, then you need to talk with whomever you got it from.

If you choose to continue to use the barrel - based on what you figure out - then you'll need to proof it again.

I'd probably start by putting the appropriate bottoming tap in the threads and see if it gets tight before running out of room, or if it stays easy to rotate all the way to the bore. If the latter, then I'd suspect the barrel has expanded a bit or it was a rather bad job of threading. IF the tap wobbles (loose or uneven tension in different directions), then I'd say you are done - the barrel is a failure.

Put a straight edge along each flat in the back and see if there is any evidence of expanding by looking at the side towards a light source. If you see evidence of bulging, even slight evidence, then you are probably done.

Sight the bore to see if there is any visual distortion in bore reflections of objects, or any evidence of lack of straightness. If so, then IMHO you are done.

Push a lead slug down the barrel from the muzzle and see if it gets looser as it gets to the threads. That may indicate an expanded bore unless it was deliberately made that way (some barrels have a deliberate taper or choke). Ask the manufacturer about the intended bore profile. Don't mention what you found out first. If they don't say choked or tapered bore, then you are done.

If there is any evidence of a problem with the barrel that isn't indicated to be a feature from the manufacturer, I'm afraid you are done. It isn't worth the risk.

If the barrel iteslf is provably ok at this point, then replace the breach plug. I wouldn't weld on the barrel or the breech plug, but that's just me. If welded, I'd be tempted to heat treat (anneal) to remove residual stresses.

Any chance there was an air pocket in the powder charge present when the proof test was made?

Gerald

Goo · « **Reply #24 on:** November 26, 2018, 06:20:18 AM »

Did I miss mention of measurements of the barrel taken before the proof test to be compared with measurements taken after the test? However it's obvious something some where stretched

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Author Topic: lose breech plug (Read 4470 times)

Dean2