Made in the USA CVA Mountain rifle question

I have an older CVA mountain rifle thats marked made in the USA, no Spain markings which leads me to think that the threads on the drum and nipple are standard and not metric? if so does anybody know the thread size on the drum and clean out screw, somebody before me has chowdered the screw and looks like they tried to use channel locks or vice grips to unscrew the drum, thanks in advance, Beav

I have two USA made mountain rifles. Both nipples are metric, I’ve never had the drums out but would bet ya lunch that they are metric. Look up Deer Creek Products. They know the CVA stuff better than anyone. They should be able to get you the info needed and probably the part also.

I have two CVA Mountain rifles (a .58 and a .50), and a CVA Hawken pistol. The plug screw in the drum on all three is metric, size M5-.8.

Please note… a 10-32 fractional screw will go right in a threaded M5-.8 hole, with minimal “wobble,” but an M5-.8 screw will not go in a threaded 10-32 hole, because a 5mm screw is .197” diameter, and a #10 screw is .190”. Seven thousandths is not enough to see, by eyeballing. I’m telling you this because you might want to put a 10-32 screw in there, and it will go. Don’t do it! Get the right screw. You don’t want it blowing out and piercing the ear of the shooter to your right because the fit was too loose. Deer Creek Products has the correct screws in stock.

Just for the record, these three guns also all use M6-1.0 nipples.

I don’t know the pitch of the CVA “drum.” While a few skilled individuals on this forum have unbreeched CVA guns and put them back together, this practice is generally discouraged. CVA developed a unique and very strong breeching system which was not meant to be disassembled. That is not a conventional drum you are dealing with. There is a photo of a cutaway CVA breech that surfaces here on the forum now and then… maybe someone will post it here. The picture will explain what I’m talking about.

Good luck with your rifle, and be safe!

Notchy Bob

EDIT/ADDENDUM: I think my CVAs are probably Spanish-made. However, Deer Creek only stocks one designated screw for this (see CVA Bolster(Clean Out) Screw ), and I would infer that the threads would be the same for all of the Mountain Rifles, regardless of the country of manufacture.

Here's the photo of the CVA breech mentioned in post #3 above:



The text describes the sequence that CVA used in breeching their barrels. Essentially, the parts are put together and torqued into place before the chamber and flash holes are drilled. If the breech is disassembled, correct alignment of the intersecting holes is critical. As noted above, several forum members who have the tools, skills, and confidence have disassembled and reassembled CVA breeches correctly, and some, such as my friend @Snooterpup , have even improved them. However, that's just not a job that most of us should tackle.

Best regards,

Notchy Bob

Notchy Bob said:

Here's the photo of the CVA breech mentioned in post #3 above:

View attachment 323704

The text describes the sequence that CVA used in breeching their barrels. Essentially, the parts are put together and torqued into place before the chamber and flash holes are drilled. If the breech is disassembled, correct alignment of the intersecting holes is critical. As noted above, several forum members who have the tools, skills, and confidence have disassembled and reassembled CVA breeches correctly, and some, such as my friend @Snooterpup , have even improved them. However, that's just not a job that most of us should tackle.

Best regards,

Notchy Bob

Click to expand...

Thanks fellas, guess I'll leave the drum alone and file and sand out the jaw marks that are in it, I will have to drill out and tap the clean out screw, the slot in this one is destroyed and there is absolutely no way to get a hold of the shoulders on it!

Beaverman2 said:

Thanks fellas, guess I'll leave the drum alone and file and sand out the jaw marks that are in it, I will have to drill out and tap the clean out screw, the slot in this one is destroyed and there is absolutely no way to get a hold of the shoulders on it!

Click to expand...

I'd just leave the screw alone, there's really no need to take it out.

Trot said:

I'd just leave the screw alone, there's really no need to take it out.

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That's what I originally thought but the guy who buys it might not feel the same!

I would be reluctant to drill it out without some sort of fixture to secure the barrel in your drill press in exactly the right place.

You might try filing flats on opposing sides of the screw head so you could get a 1/4" open-end wrench on it. Another possibility might be to simply hacksaw a new slot in the screw head at right angles to the old one, so you can turn it out with a screwdriver. With all of these suggestions, obviously, you need to be careful to not damage the drum.

With some trepidation, I will say I have had some success getting stuck round head screws out of various appliances with Vise-Grips, although I don't specifically recall using one on a gun. We are just talking about that little round-head plug screw here, which is evidently already damaged beyond salvation, and not the drum. Try to latch onto the screw head without touching the drum and use the Vise-Grips to turn it out.

If you think the screw is really stuck, consider soaking the breech of your barrel in penetrating oil or kerosene for a couple of days first, and then heat the drum a little with a propane torch before attempting to turn out the screw. The threaded portion of that screw is only about a quarter of an inch long, so it should not require all that much torque.

I would try one or more of those things before drilling it out.

Good luck with it.

Notchy Bob

Notchy Bob said:

Here's the photo of the CVA breech mentioned in post #3 above:

View attachment 323704

The text describes the sequence that CVA used in breeching their barrels. Essentially, the parts are put together and torqued into place before the chamber and flash holes are drilled. If the breech is disassembled, correct alignment of the intersecting holes is critical. As noted above, several forum members who have the tools, skills, and confidence have disassembled and reassembled CVA breeches correctly, and some, such as my friend @Snooterpup , have even improved them. However, that's just not a job that most of us should tackle.

Best regards,

Notchy Bob

Click to expand...

Agreed if it ain't broke I normally don't try to fix it.