“New” barrel thread for k frame w/ shroud

[-BTM-]

Anyone know what the new barrels are threaded for?

Edit: please don’t say so it will screw into the frame

 

[Shotguncoach]

It's not so that the barrel can screw into the frame. It's so that the barrel can be mounted in a vise and the frame can be threaded onto the barrel.

Had to do it

 

[WR Moore]

Ah, he's asking about 2 piece barrels. Does pose an interesting question about what gets cinched in a vise while torquing the barrel (with flange at muzzle)/barrel nut. Presume frame, but I'd be interested to know.

While I've never seen one, I don't see any particular reason that S&W would change their thread specs after over a century. Perhaps someone with actual knowledge will chime in.

 

[-BTM-]

Here is an example of- a 2.75” k frame model 66 barrel.

It looks like there is a step down from the major diameter of the threads, I’m curious about compatibility with the .540/36 K frame threading.

 

[WR Moore]

It looks like a step down TO the OD of the threads. You can figure that out real easily if you have a micrometer or caliper. If there's a local machine shop, they'd probably measure it for you, thread spec included.

0.540 is a smidgen under 9/16 in (0.5625 in) if you just want to have an educated guess.

OK, even if it's compatible, you'd need a shroud and have to alter the frame to install an alignment stud for the shroud. And, source the shroud. Whatever you have in mind is likely to be expensive.

 

[-BTM-]

OK, even if it's compatible, you'd need a shroud and have to alter the frame to install an alignment stud for the shroud. And, source the shroud. Whatever you have in mind is likely to be expensive.

Well, I’m shopping for a lathe so yeah it is LOL

On the other hand, I could go to MGW and buy the parts needed to turn a compatible J frame into an 8 shot .22 snubbie for $250

 

[steelslaver]

I bet they are not the same as the normal 1 piece barrels. I have a 2 piece insert for an L frame and it is considerably larger than a one piece L frame barrel.

What I do know

J frame .500-36 one or 2 piece
K frame .540-36
L frame .562-36 one piece, 2 piece 44 mag .638-36
N frame .670-36 one or 2 piece

But, there is a 2 piece 66-7 barrel on Ebay for $44.99 + $4.99 shipping . so you could have both the answer and parts in your hand for $50.

I am tempted to get it myself.If you don't PM me and I will if you don't. But, I won't be home for about a month to measure it.

 

[steelslaver]

OK, I bought the barrel on EBay and will report the size of the threads when I get home and open all my "presents" I have bought myself while working.

 

[-BTM-]

Took one for the team, good man. I didn’t see this in time.

 

[steelslaver]

This has been rolling around in my head. I don't see how they could change the size of the barrel shank on K frames. If they made it smaller it would be even more prone to cracking at the bottom of the forcing cone than it already is. If they made it larger the area between the bottom of barrel and the yoke would need to be thinner than it already is. if they made the frame thicker there, the cylinder would need a larger center line to chamber radius which would mean an very thin outer wall unless you made the cylinder OD larger and then you basically have a L frame cylinder

I think that its gonna be the same as the one piece barrels

 

[snw19_357]

This has been rolling around in my head. I don't see how they could change the size of the barrel shank on K frames. If they made it smaller it would be even more prone to cracking at the bottom of the forcing cone than it already is. If they made it larger the area between the bottom of barrel and the yoke would need to be thinner than it already is. if they made the frame thicker there, the cylinder would need a larger center line to chamber radius which would mean an very thin outer wall unless you made the cylinder OD larger and then you basically have a L frame cylinder

I think that its gonna be the same as the one piece barrels

Thanks to my adventure in the other thread I have learned the thread on the K-frame two piece barrels is the L-frame thread (not M69) .562" x 36 tpi... They DID make the area between the bottom of barrel and the yoke thinner!! Ridiculous!