Alloy frame problems

[ploz357]

I was interested in purchasing an alloy frame smith and was taken back by an issue with frame cracking. Is this a common occurrence with the airweights or simply abusing a gun thru reloads causing problems? Are the j (37,38)frames more susceptible than say the k (12) frames?

 

[OHIOUP]

I think abuse by exceeding ammunition rating would be the most likely cause of frame cracks. There are a bunch of well shot uncracked airweights out there. I carry one almost everyday. I shoot it bi-weekly and don't lose a bit of sleep worrying about cracks.

 

[smithman]

Over-torqued barrels could do it too.

 

[ImprovedModel56Fan]

I think abuse by exceeding ammunition rating would be the most likely cause of frame cracks. There are a bunch of well shot uncracked airweights out there. I carry one almost everyday. I shoot it bi-weekly and don't lose a bit of sleep worrying about cracks.

I don't actually KNOW much of anything, but I read a lot, and the consensus seems to be that exceeding ammuntion rating is NOT the most likely cause of frame cracking, but, rather, that it is usually caused by overtorquing the barrel during installation at the factory. I believe that the factory has either implicitly or explicitly confirmed this. I have seen it on a 12 and on a 42, and, for some reason, have not heard about it much on 37's. Probably just that I haven't heard much. One poster here did an extensive test on a 12 with +P, and had no problems. Probably failed to get one with an overtorqued barrel, which, I understand, can just about crack sitting in the box.

I am sure that more knowledgeable folks will chime in on this.

 

[ploz357]

Thanks for some insight.I do not have a airweight yet but hope to purchase one.I kind of surmised that you have to abuse them to have that resulting failure.

 

[mkk41]

Own 2 Mod.37s. Both have had a few hundred factory +Ps thru them. No stretching , no loosening , no cracks.

 

[Malysh]

Maybe I've been lucky. I've got a Centennial Airweight(1954), a Mod 37(1962) and a Mod 38(1969), none of which have overtorqued barrels and none of which have cracked frames. I don't shoot my 1954 M&P Airweight 2" 38 Special with the aluminum cylinder, though.

I carry the Mod 38 many days of the week though sometimes I carry a larger caliber and large frame semi auto pistol. In the summer I've gotten to the point where I almost never carry anything but the Airweights.

 

[OHIOUP]

I was just wondering if you could overtorque a pinned barrel? I've just recently seen a cracked airweight frame. A model 38 manufactured in 1978.

 

[TOMFD]

I actually bought a Nickel 37 at a very respected local store this fall and after cleaning the gun very well saw "THE" crack .I called the store the next day and brought it back and was reimbursed fully . I was standing there when the clerc called the owner and heard the owner saying he only put a few rounds threw it . Most of the grime I cleaned was pocket/sock drawer grime and i believe it was not shot a lot and the barrel was overtightened at the factory . Just my opinion ,,,,,,but will now "Examine" the problem areas when looking at these gems .
Tom C

 

[ImprovedModel56Fan]

I was just wondering if you could overtorque a pinned barrel?

Both that I've seen were pinned barrels. Not sure what you mean by "you." It is S&W that overtorques the barrels (on very rare occasions).

 

[redlevel]

I actually bought a Nickel 37 at a very respected local store this fall and after cleaning the gun very well saw "THE" crack .

Where does "THE" crack usually occur? Can someone direct me to some images of cracked frames? I am looking to buy a couple of airweights in the near future and I would like to know where exactly to look. I own and have owned a bunch of j-frames, but never an airweight.

 

[OHIOUP]

Model520Fan...by using the word "you," I meant any person, especially the person at the factory who puts the barrel on the frame.

To restate my question more clearly: How is torque involved in pinning a barrel to a frame? I understand how too much torque may contribute to frame cracking with a threaded barrel.

redlevel... the crack occurs where the frame is very thin just under the rear end of the barrel in the area which would be just above the top of the crane when the cylinder is closed. The crack is parallel to the long axis of the barrel.

 

[faraim]

If anyone has photos of this it would make for a very informative sticky!

 

[ImprovedModel56Fan]

Model520Fan...by using the word "you," I meant any person, especially the person at the factory who puts the barrel on the frame.

Sorry. That IS the normal use. I just wanted to make sure we were talking about the same thing.

To restate my question more clearly: How is torque involved in pinning a barrel to a frame? I understand how too much torque may contribute to frame cracking with a threaded barrel.

Again, sorry if I misunderstand a clear question. Most folks here, when talking about a pinned barrel, are talking about a barrel which is screwed into the frame AND has a pin through the frame and just slightly into the threads of the barrel. I don't know what the specs are for tightening the barrel before pinning it, and if that was your question, I'll have to tell you that I simply don't know the answer. I did look up in Kuhnhausen that a new barrel should compress threads or shoulder or whatever for 1/8 of a turn after meeting a properly trued shoulder, except for .22 and .38 bull barrels, which should go only 1/10. What torque this works out to, I don't know. I also don't know whether the specs are different for unpinned barrels, but I'll bet that they don't torque them any less. Regardless, my guess would be that even for a pinned barrel, the torque is considerable, and probably close to max, at least for an alloy frame, otherwise they wouldn't have had occasional problems.

I hope I answered what you were actually asking. Perhaps a gunsmith or an S&W-trained police armorer will chime in and tell you how it really is.

 

[OHIOUP]

Thanks Model520Fan. I don't think I had a good picture of the process but you turned the light on for me.
So whether pinning or not pinning the barrel, it's having the threads of barrel and frame mating in such a way that after so many turns and with specified torque the sight is perfectly straight up and down?

 

[ImprovedModel56Fan]

Thanks Model520Fan. I don't think I had a good picture of the process but you turned the light on for me.
So whether pinning or not pinning the barrel, it's having the threads of barrel and frame mating in such a way that after so many turns and with specified torque the sight is perfectly straight up and down?

I think so, pretty much. Except apparently Kuhnhausen says that the way to do that is to allow 1/8 turn (or sometimes 1/10 turn) remaining when the barrel and frame meet squarely, properly and tightly. He does not actually specify a torque, and I do not know what S&W's procedure is. Perhaps it is the same.

 

[s&wchad]

My PC 625-10 (alloy N frame .45 ACP) developed a crack while I was shooting it. The cylinder rubbed the back of the barrel while I was opening it to reload, I noticed the crack and stopped shooting. S&W gave me a different gun under warranty (my choice).