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50 cal. CVA barrel repair.

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I was taking the scope I had on my CVA Missouri 50 cal. 28" barrel off to re-blue and clean it back up after a lot of years. I had the front mount off, then started on rear mount. The last screw rounded off. So I thought I'd drill it out. Long story short, I accidentally punched through the barrel. The drill bit was small. Same size as the small screws on the mounts. The hole is just ahead where the breech plug front end is in the barrel. Was told that welding the hole, then finishing the barrel would not be a good idea because of the pressure buy the powder firing. My question is, would tapping that small hole and threading a hardened plug in it, would it be able to withstand the pressure? I also thought about cutting the barrel back 2". That is about where the front of the breech plug is located. Then re-tap for breech plug. Thought I would get some thoughts on this. Thanking you all in advance.
 
no expert. but i figure that if a threaded in percussion drum stays put that a fine thread plug should also. ???? green loctite ? just have to watch that its flush inside to prevent fowling from having a place to hide. again no expert.
Thanks 2 shots. That is kinda what I thinking too.
 
Just in front of the breach plug.You got lucky there. Thread the hole. Use a screw just long enough to get even with the bore and just above the outside. You don't need it to be hardened. Use red or green locktite. Put the screw in and let it harden. File off the top and done.
n.h.schmidt
 
I agree with plugging the hole with a suitable threaded screw but rather than using a Loc-Tite compound which does little to actually seal the threads, use a thread sealant like Permatex makes. It's shown in the link below

https://www.amazon.com/Permatex-592...t=&hvlocphy=9061144&hvtargid=pla-434501655098
As far as strength goes, if the hole is threaded for a # 6-40 screw there will be about 140 pounds of pressure trying to blow it out of the hole if the breech pressure is at 10,000 psi. Torqued to the recommended 12.7 lb/in, a #6-40 screw will produce over 460 pounds of force so that 140 pounds it will receive when the gun fires with a very heavy powder load won't bother it at all.
 
Just in front of the breach plug.You got lucky there. Thread the hole. Use a screw just long enough to get even with the bore and just above the outside. You don't need it to be hardened. Use red or green locktite. Put the screw in and let it harden. File off the top and done.
n.h.schmidt
Thanks for your reply. I think I'll go ahead and try set set screw.
 
I agree with plugging the hole with a suitable threaded screw but rather than using a Loc-Tite compound which does little to actually seal the threads, use a thread sealant like Permatex makes. It's shown in the link below

https://www.amazon.com/Permatex-592...t=&hvlocphy=9061144&hvtargid=pla-434501655098
As far as strength goes, if the hole is threaded for a # 6-40 screw there will be about 140 pounds of pressure trying to blow it out of the hole if the breech pressure is at 10,000 psi. Torqued to the recommended 12.7 lb/in, a #6-40 screw will produce over 460 pounds of force so that 140 pounds it will receive when the gun fires with a very heavy powder load won't bother it at all.
Thanks for your advise. Will try the tapped insert screw. Sounds like it will withstand the pressure.
 
They take pretty good pictures;

large barrel.JPG
 
Presumably in the OP’s case the screw would be below where the ball would sit – within the powder area – so a small protrusion would be acceptable. After all, the end of the screw would be flat and the bore curved. Would that be right?
 
If you used a small diameter drill and punched through, was it a small enough diameter that you could tap the hole 2-56 or 4-40?

A 2-56 requires a #50 drill (0.070")

A 4-40 requires a #43 drill (0.089")

It may be possible to use the punch though hole for a small diameter screw and then still have room for the scope mount screw.
 
Because you probably can't remove the breechplug from your barrel I would buy a cheep bore scope camera off eBay so you can see exactly when your screw is flush with inside of the bore.
https://www.ebay.com/itm/6LED-7mm-A...807447?hash=item5b86748657:g:CZ8AAOSwXixcosTP
I soaked the breech plug with Kroil oil for a few days. Then I wrapped the barrel with leather to put in vise. Used a cresent wrench with medium effort, and the plug came out easy without damaging the threads or plug. Guess I was very lucky. Thanks for your reply, Have a great day.
 
If you used a small diameter drill and punched through, was it a small enough diameter that you could tap the hole 2-56 or 4-40?

A 2-56 requires a #50 drill (0.070")

A 4-40 requires a #43 drill (0.089")

It may be possible to use the punch though hole for a small diameter screw and then still have room for the scope mount screw.
That sounds like a good option for reusing the scope. Thanks.
 
Presumably in the OP’s case the screw would be below where the ball would sit – within the powder area – so a small protrusion would be acceptable. After all, the end of the screw would be flat and the bore curved. Would that be right?
I hope it set screw ends up being flush with inside of barrel. To answer your question, I don't know. When this is all set and done, I'll try and post some pictures, and try a few shots with it. Thanks for the reply.
 
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