Breech plug won't budge

[azmntman]

Hunting can be excellent exercise!

 

[Flintandsteel]

I've probably pulled the plugs on at least 30 Rice barrels. Never had to whack them or use anything but my little 24" plug wrench and maple vise jaws.

 

[flntlokr]

Recently rec'd a new kit from a reputable supplier. It has a Green Mountain barrel, with the breech plug installed. I need to get it out for two reasons, firstly to set the barrel down and back squarely against the wood, and secondly I want to file a taper on the lug of the plug.

I can't get the plug to budge. Clamped well in a pattern maker's vise and using a 15" Crescent wrench just broke the wooden jaws. Made new jaws of oak, they broke too. Tried soaking inside and out with Kroil for a week, no improvement. Tried heating the breech with a heat gun, still no rotation. Bought a better vise, a big one with 6" jaws and four hold down bolts. After fitting protective plates of heavy brass sheet I put a two foot pipe extension on the wrench handle and only succeeded in lifting the end of the bench off the floor.

Any suggestions? I've already contacted the supplier for help, the pipe extension was their idea. Green Mtn is not answering their phone. I'm about ready to ship the barrel back to the supplier.

Leave it alone and work around the wood fitting and filing. Your chances of messing up the barrel or plug are pretty good if you persist.

 

[flynfred]

I ran into a few rifles where the drum is threaded into the breach plug , if that's the case you have to remove the drum first

 

[Kansas Kid]

Yep, also vent liners can be hitting plug threads

I ran into a few rifles where the drum is threaded into the breach plug , if that's the case you have to remove the drum first

 

[FishDFly]

"ATF & acetone"

The specific gravity of ATF and acetone are different and will separate initially, acetone will float on top. You will have to shake up the mixture in a closed glass bottle for quite some time for the 2 to go into solution. If not the acetone will evaporate and all you will have is ATF.

 

[user 34300]

If you use metal V-blocks you catch two flats. Steel blocks are excellent, line them with business cards. The barrel will not twist and get buggered up.

If you do use wood, use maple. Make the blocks fit the barrel closely and use powdered rosin. Using copper, lead wood, or whatever to line the jaws of and ordinary bench vice is inviting disaster.

"I ran into a few rifles where the drum is threaded into the breach plug , if that's the case you have to remove the drum first"

If you paid for for that demand a refund.

 

[Maineshops]

My 40 year old Hawken barrel was tough too. Had to make smooth steel plates for huge vice. Wrapped the barrel with leather. Used a pipe to tighten the vice till I thought the vice would break. Wrapped breach plug with padded steel plate. 16" pipe wrench and cheater pipe. Put my 270 pounds on it, a propane torch and bounced. After about 40 minutes of heating a cooling it finally broke loose. Thought the table was going to flip over.

Heat the breech plug too lot to youch then put about a mouthful of kerosene down the barrel. The heat will draw the kerosene through the threads

 

[longcruise]

whose kit is this? I don't think Green Mountain installs breech plugs with the exception of their IBS drop ins.

I'd just leave it alone and work around the problem.

 

[stewart.leach]

This is not my first rifle building rodeo. On previous guns I fitted the breech plugs myself, using files and blue spotting compound until the fit was close, then did final adjustments with stones for a smooth fit. Always coated the threads copiously with anti-seize compound before final assembly. Tightened with the 15 inch Crescent wrench using body weight and a few whacks with a 1 lb dead blow hammer. Perhaps I should tighten more than I have been, but have seen no evidence of plugs loosening.

Right now I am waiting on a 3 lb hammer, while letting the ATF & acetone mix soak inside and out. It seems my hammer collection has a major gap between 1 lb and an 8 lb sledge.

In the meantime I have been polishing the lock externals. Gotta love silicon carbide abrasive paper, assorted small dowel sections and popsicle sticks. Ran out of abrasive cords last year, should have ordered more. Slow going as mid-70's thumb joints start complaining.

 

[longcruise]

Where do you get the abrasive cords? Seems like they would be very handy.

 

[Kansas Kid]

I see no reason why a breech plug should be very tight. Something like 30 ft lbs should be plenty.

 

[M. De Land]

Yeah, if the shoulder fit is good one does not need to thread tighten until they smoke.

 

[Eric Krewson]

You might get a cheap borescope off ebay and see what is going on down at the breech. I have one rifle with the touchole liner screwed into the breech plug.

 

[nhmoose]

Also the liner is way to long IMHO

 

[Zonie]

Quite frankly, I think it is a very poor idea to over tighten a breech plug. By over tighten I mean any torque greater than around 60 lb/ft.

My reason for saying so it, a thread only has so much strength.
Now, if much of the threads strength is being used just to hold the plug tightly in place, the amount of strength it uses must be subtracted from the total strength the threads have. The threads have an important job ahead of them. That is to contain the pressures of the explosive gasses produced by the powder when the gun fires.

In other words, the strength of the threads is limited. We don't want to use up the strength that is available to keep the breech plug from blowing out by spending it on just clamping the breech plug against the shoulder in the barrel.

 

[Relic shooter]

Good point Zonie, you may recall a a few decades ago when Thompson Center shooters experienced some breech plug failures due to over-tightening their cast breech plugs.
I was present at a match when the breech plug failed where the threads meet the barrel, this was on one of my customer's TC Hawken.
Happened along time ago but as I recall TC then replaced the cast breech plugs with machined ones.
Fortunately my customer only suffered minor bruising but the rifle was a total loss but TC promptly replaced the rifle along with some added accessories as a bonus..

 

[Kansas Jake]

I don’t understand over torquing breech plugs. It is like a wheel where vibration will cause them to come loose.

 

[Relic shooter]

Some modern day production black powder firearm producers used air powered tools to seat breech plugs. If the torque setting was set too high the sudden stop could fracture the threaded area where the breech plug meets the barrel, especially if the breech plug was cast.

 

[longcruise]

Call Bobby Hoyt and ask him how he does it. With all the rebores he does he must encounter some real bears.