I know this is a tricky move but I have a N.O.S. 3" airweight barrel I would like to put on my 2" Mod 37 both are P&R.
Thanks,
Ischia

It's been reported here that the factory won't do barrel changes on aluminum frames. There appears to be a substantial risk of frame destruction. If you look about here, barrel changes on steel J frames aren't without risk.

I'd suggest having a qualified pro with the proper tools give you an estimate and be prepared to lose both fee and firearm. Possibly not immediately, but down the road. If it ain't broke, don't fix it.

I would never change a barrel on an aluminum revolver! Tempting fate way too much!

FYI: Model 37s were "P" but NEVER "R".
P indicates pinned barrel. R indicates recessed cylinders. Only rimfire and earlier magnum calibers had that feature.

And competent gunsmith should be able to do the swap.

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Chris
SWCA #2243 SWHF #292

It's just too risky. The frame is very thin under the barrel - that's where the vast majority of cracks occur. Think about it - turning the barrel out to remove it will put a tremendous amount of torque right there at its weakest point. If it doesn't crack during removal, you still have to put in the new one.
I'm all for barrel swaps, having done (thru a gunsmith, not myself) a dozen times over the years... but never on an alloy frame. Your best bet is add that barrel to a steel frame.
Best of luck.

I recently picked up a model 12 from a member here that has a corroded cylinder and barrel. I have already changed the cylinder using one from my 10-7 J&G sales gunsmith specials. I am debating the barrel change. The outside is nasty and there is some pitting inside.

Pat of what worries me is knowing that their may well have been some galvanic corrosion between barrel and frame. If I do it I think I will set the frame up in mill. Trim it under 1/4" from frame then drill and ream the barrel to just under treads minor diameter and then remove the threads. Clean up with a K frame tap in and then fit new barrel.

I tried the barrel on the model 12 with my frame wrench and planned to stop if if it took much effort. Hardly took any at all. old barrel is off and new one just needs front sight added before bluing and final fitting. New barrel was made by turning shoulder way way back on an messed up model 14 barrel and adding threads. This moved barrel lug back to spot for short ejector. Cut forward portion off to just in front of lug.

The Model 12 is way different than the current aluminum alloy J frames. The newer guns use a crush fit to hold the barrel in place. I would listen to all the suggestions above to leave it be. ( I think that's right but I'm no Smith)

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Freedom is never free!!
SWCA #3437

The pin has NOTHING to do with the barrel not moving if a pinned model is not torqued exactly like a non pinned model the barrel moves. Take a barrel that is pinned and turn the shoulder back, then reinstall it to its original position and insert the pin. It will easily move about 5 degrees in either position. Been there done that. The amount of torque pinned or non pinned varies some and is not very much. I have removed barrels for quite a few pinned and non pinned guns

The "Crush" never has been a real thing, it is something made up by people who have never removed or installed barrel It has always been the pressure of the shoulder again the frame. A true crush fit requires something that crushes.


The model 12 and 37 are both aluminum framed gun with almost exactly the same amount of material between top of yoke cut out and barrel. The 12 is a K frame true. A k Frame barrel shank is .540-36 and a J is .500-36. But the K shank extension needs about an .04 flat on bottom so the gas ring clears. That is because top of yoke is so close barrel.

I will say you run more of a risk of frame damage on alloy guns than steel. But that is always going to be true when you work with a weaker material no mater what you are doing

What dash # is your 12? Or does it have a dash?

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SOS USA

12-2 It did have a pin. I put my frame wrench on relatively tight. But, it did not take much to torque break it loose. I have had pinned guns that were much tighter. I had a back up plan if it didn't come easy.

I've always had an interest in the model 12. I've owned probably 5-6 along the way. They were always dash 2 or 3. Never owned an elusive dash 4 with the standard width frame. I got pretty good at shaving down the back of standard K frame grips to fit the narrow frame 12's. I once owned 12-2 SB pencil barrel 4" nickel ANIB. I've never seen another. Most 12's for sale 20yrs ago when I was collecting, seemed to be dash 2-3 SB 2inchers. Never saw a cracked frame. Sorry for the thread drift.

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SOS USA

Drift or not, Interesting none the less.

Here is something else interesting. When I put a 10-6 cylinder in the 12 with the original barrel the barrel gap was huge. The 12-2 cylinder is shorter than any of the K frame 38 cylinders I have in my parts pile. I might have lived with the original barrel if it hadn't been for that.

What's holding any threaded fastener is actually a very slight stretch/longitudinal tension on the bolt, not a crush. When working on much larger industrial bolts/studs we used a couple of different installation methods. One was stretching the stud with a hydraulic jack and turning the nuts down hand tight (several passes and a check pass). The other involved measuring the internal length (from head of bolt to an internal reference point) of each bolt with a special depth micrometer. Then, after installation, measuring the stretch. If not within spec, further tightening was required, and checked.

A lot of automotive differential pinon nuts are crush nuts intended to only be used once.