loose breechplug on french Mle 1822 T

[bigbirdiscool]

Hello everyone,

i recently acquired a french Mle. 1822 T smoothbore musket (percussion conversion).

i took everything apart to clean it and do some restauration on the stock.
after cleaning the barrel i soaked it in penetrating oil for an hour to remove the percussion nipple, it came out without any problems.
after that i noticed the penetrating oil did such a good job i could unscrew the breech plug by hand.
on the underside of the barrel there is a mark which lines up with a mark on the breech plug, but when i reinstalled the breech plug i noticed i could turn the breech plug past that mark before it tightens.

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i did a careful measurement and found out there is 0.1mm play between the breech plug and the face of the barrel when the marks are lined up.
the threads in the barrel and on the breech plug are in good condition, they are the same diameter as the inside of the barrel so there is no shoulder inside the barrel, the breech plug only tightens down on the face of the barrel.

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would it be safe to use a 0.1mm shim so the breach plug can be tightened down with the marks lining up? someone suggested to use some form of loctite on the threads in addition to the shim but i'm not sure that is the way to go.

 

[Col. Harrumph]

I really have to wonder if that breech plug isn't a replacement. Surely Loctite isn't the answer, and where exactly would you put a shim?
Really, the only safe fix that I can think of is to find a machinist who will weld metal onto the plug and re-cut the threads. You might ask Mark Novak, proprietor of the "Anvil" Youtube channel.

 

[Blue68f100]

There is some Loctite #290? ( not in my shop to confirm) that might do the job. It's designed for filling gaps in sleeves. 0.1mm is only 0.004", about the thickness of some paper.

 

[bigbirdiscool]

i have checked, all parts on the musket have matching numbers
the idea was to make a washer out of 0.1mm thick sheet metal to put between the 2 little flats on the breech plug and the face of the barrel, just like you would put a washer on a bolt.
i've tried to look for an email adress for mark novak but can't find one. i dont have any social media so i cant contact him on instagram or youtube.
have sent an email to c&rsenal a few days ago but they get hundreds of emails so i'm not sure if they have time to reply.

 

[Col. Harrumph]

https://milvetsandpatriots.com/tag/mark-novak

 

[ApacheCoTodd]

Aside from the ablity to tighten past its registration mark.. If you stop at the mark, how much side-play does the thread mating allow? If any play, is it generally the same in any lateral direction?


Todd.

 

[bigbirdiscool]

i'm not really shure what lateral direction is.
i tried axial and radial but cant feel any play in those directions.
when i push the breech plug at an angle from the barrel bore axis there is play, i dont know how this is called but in aircraft and vehicle movement they call it yaw. not sure how to measure that but it is definately there.
also the treads on the breech plug seem to be slighty conical.

 

[ApacheCoTodd]

That answers my question nicely.

In the case of your description, I would use silver-solder with a form of a jig to mimic their situations relative to the stock.

Todd.

 

[beag_nut]

That answers my question nicely.

In the case of your description, I would use silver-solder with a form of a jig to mimic their situations relative to the stock.

Todd.

I think your idea of making a shim from thin sheet metal is the answer. I would guess that over time the threads had corroded enough to lose metal, creating the gap you originally saw.