Threads on barrel

[bpd303]

I've replaced two drums on CVA rifles, obtained from Deer Creek. One drum had the nipple blow out. I replaced the nipple with an over size thread one. It also blew out. The owner regularly used a 150 gr fffg powder charge and I found out the clean out screw had been drilled and tapped for a larger screw, which didn't leave enough material to hold the nipple. A new drum and nipple fixed it.

The second one had the same problem the OP has. It was fixed using red Loctite but the drum threads had stretched to the point the drum also blew out. Lucky it didn't hit anyone. The threads in the breech plug were fine and a new drum tightened and indexed just fine. Last I knew the rifle was still going fine and the owner no longer removes the drum. It is my experience the breech plug is made from stronger steel than the drum so if threads let go it's the drum threads not the breech plugs.

 

[BS]

https://www.harborfreight.com/9-pie...ore=&msclkid=22ba725943821488a91816b68c2a3ea1
The link is to: Harbor Freight

LIFETIME CARBIDEPunch and Die Set, 9 Piece​

Punch out some feeler stock and place the doughnut under the drum.

Use a pop can to test thickness.

 

[R Ellis]

I've replaced two drums on CVA rifles, obtained from Deer Creek. One drum had the nipple blow out. I replaced the nipple with an over size thread one. It also blew out. The owner regularly used a 150 gr fffg powder charge and I found out the clean out screw had been drilled and tapped for a larger screw, which didn't leave enough material to hold the nipple. A new drum and nipple fixed it.

The second one had the same problem the OP has. It was fixed using red Loctite but the drum threads had stretched to the point the drum also blew out. Lucky it didn't hit anyone. The threads in the breech plug were fine and a new drum tightened and indexed just fine. Last I knew the rifle was still going fine and the owner no longer removes the drum. It is my experience the breech plug is made from stronger steel than the drum so if threads let go it's the drum threads not the breech plugs.

Better watch out cause I suggested the same think and was basically told it was a 1 in a million chance it would line up even after the one I did lined up perfect just like yours

 

[bpd303]

A lot of folks who replace a drum, or remove it for whatever reason, have a tendency to over torque them when installing it again. What is fun on a CVA is to index the breech plug if you have to remove it. I had to take out a breech plug on one I purchased at a pawn shop. I made a thread about that one. I found the thread.
https://www.muzzleloadingforum.com/threads/cva-54-hawken-for-the-record-books.95771/A companion thread.
https://www.muzzleloadingforum.com/threads/cva-50-hawken-nipple-blow-out.96611/

 

[shorthair]

Typically something you would make from shim stock that would require you to have shim stock and a punch and die shim making set. Realistically you are likely looking for shims that are .001” or .002” thick. Search on line if you must and see what you find. And once you get your existing or replacement drum clocked to the correct position suggest you dispense with removing it each time you shoot and clean the gun. For reference, believe good old aluminum foil (the WRONG material for a shim in this instance) is around .003” thick.

But for what you are looking to do or repair, a ‘permanent’ sealant like one of the Loctite products is a good option, as long as you set it and forget it. Wish you luck.

For a small one off I would just pick up a feeler gauge, but for the OPs use I agree with the Locktite suggestion.

 

[shorthair]

A lot of folks who replace a drum, or remove it for whatever reason, have a tendency to over torque them when installing it again. What is fun on a CVA is to index the breech plug if you have to remove it. I had to take out a breech plug on one I purchased at a pawn shop. I made a thread about that one. I found the thread.
https://www.muzzleloadingforum.com/threads/cva-54-hawken-for-the-record-books.95771/A companion thread.
https://www.muzzleloadingforum.com/threads/cva-50-hawken-nipple-blow-out.96611/

My understanding of CVA breach plugs is that they're not designed for ease of removal to put it mildly.

 

[bpd303]

I had no trouble removing the breech plugs. One must have the right fitting tools and padded vise jaws to firmly hold the barrel just forward of the breech plug. If the barrel is clamped at the breech plug threaded area it will make removal difficult. First the drum must be removed, then when reinstalling the breech plug it must be torqued just enough to allow the drum to be inserted. I forged a box wrench to fit the breech plug.

 

[Greg Y]

Better watch out cause I suggested the same think and was basically told it was a 1 in a million chance it would line up even after the one I did lined up perfect just like yours

Sorry to drag this up, but this is something I deal with and hopefully my response helps someone.

When needing to align any threaded to a shoulder item....barrel, drum...etc, measure the thread pitch. If the pitch is known, divide the pitch to get the number of depth per rotation. 16tpi is .0625" per revolution for example. If you need a half of a revolution, divide the .0625 by 2. A quarter....by 4 etc.

Doing so can help you determine exactly how much shim is needed before crush occurs.

 

[Dusty_Traveler]

Sorry to drag this up, but this is something I deal with and hopefully my response helps someone.

When needing to align any threaded to a shoulder item....barrel, drum...etc, measure the thread pitch. If the pitch is known, divide the pitch to get the number of depth per rotation. 16tpi is .0625" per revolution for example. If you need a half of a revolution, divide the .0625 by 2. A quarter....by 4 etc.

Doing so can help you determine exactly how much shim is needed before crush occurs.

Very helpful maths. Thank you!