I have three Airweights (two 37s & a 12) that do not have this issue. However, I read about this being a common problem with this frame. Can the frame be fixed? If not, Why? If it can,how is it done?

I hope I never have the problem. But, I'm curious....

Best,
Charles

Repairable only with a new frame. It seems to be quite rare, actually, judging by the posts on this forum, which probably attract every cracked frame story available. My 642 is 8-9 years old and only beginning to show some wear. Model 12's seem to be a little more prone ... Somebody else is going to have to explain why you can't successfully weld aluminum alloy in a gun frame.

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Some collect art; I shoot it!

Not all that common, but it does happen. The alloy frame cannot (will not) be repaired. Most of the ones I've heard about here on the forum have been replaced with a similar frame if one is available....and if the damage was shown to be caused by a defect in material, and not neglegence or modification by the owner.

I'm not a welder, so I have no idea why the frame cannot be repaired. I'm assuming it's because the repair would cost more than a new frame.

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Ret. LE, FA Instr, S&W Armorer

It can not be welded because the type of aluminum alloy (7075) used in fire arm frames is not weldable. It is also needs a heat treatment. It will fuse, but the weld effected zone on each side of the weld will have to much heat induce stress and will fail. No way to weld and heat treat the weld effected zone. No way I would even try it and I know guys that can weld 2 beer cans together and never blow a hole. Some gun parts are 6061 which is a bit more forgivable, but usually not use in the frame itself.

Read this: Aluminum Workshop: What’s so bad about welding 7075, 2024? - The Fabricator

and from another source

"material can become susceptible to stress corrosion cracking after welding. This phenomenon is particularly dangerous because it is not detectable immediately after welding, and usually develops at a later date when the component is in service. The completed weld joint can appear to be of excellent quality immediately after welding. However, changes which occur within the base material adjacent to the weld during the welding process, can produce a metallurgical condition within these materials which can result in intergranular micro cracking, which may be susceptible to propagation and eventual failure of the welded component. The probability of failure can be high, and the time to failure is generally unpredictable and dependent on variables such as tensile stress applied to the joint, environmental conditions, and the period of time which the component is subjected to these variables."

I looked into it. Brother is a certified welding inspector with lots of reference material and he agrees.

On a steel gun (4140-4150 alloys) you could probably make a brass insert, bevel the crack, heat the frame up to about 450f and tig weld with 70 series filler. Remove the brass insert, put the frame in an HT oven (I have one) heat it up to about 850f hold it for 2 hours and then drop the temp about 50f an hour till it was around 350 f. This is a stress relief and as every S&W frame I have checked with a hardness tester is relatively soft it would not ruin its temper. Then retap the threads and machine that part of the yoke cut. Still your doing a repair in a thin section. I might try it in a K38 or something and see what happened. If it failed again it wouldn't be catastrophic, just recrack.

well sadly these frames are just not able to be saved....this is the main reason why have always been a little leery of them..but Dad has carried one for 23 years and has shot his a lot and never had any issues...i think when some people over due it with hot ammo or abuse them they might have a issue...but with such little issue i have heard of it for many years...i think Smith just takes care of those with any issue....Thank God we have not had lots of issues like other manufacturers do...God Bless,John

Are the semi auto alloy framed guns made of the same stuff?

"Are the semi auto alloy framed guns made of the same stuff?"

I don't know but I DO know the application is different. The S&W J and K frame Airweights tend to break in the same place, on the frame where the frame is threaded to accept the barrel to be then torqued so it won't unscrew with use.

I had written S&W several letters in the 1985 era urging them to build the Model 642. I was thrilled when they did and I bought my first one, BKA1072, 4-22-91. Then I bought a spare.

I qualified with my first Model 642 at a minimum of 50 rounds of Plus-P Federal for 20 years, twice each year qualifying. Then, cleaning my gun after a qualification in 7-2011 I spotted the cracked frame, in it's most common place, on the bottom of the frame where the barrel screws in.

I then took another box of Federal +p out to the range and shot them, and the 642 worked fine.

S&W replaced my original 642 with a 642-PRO. Took less that two weeks




















f

7075 (and those similar to it) are the alloys used for most ARs and I would think most handguns.
It is one of the strongest aluminum alloys and will precipitation harden and allow higher yield strengths, but also makes it hard to weld. They can be welded, but only in heavier sections and for low stress applications like molds etc. 7075 is also used a lot in airplanes. Notice how the wings and fuselage are riveted and not welded. 2024 is also a very high strength alloy, but it suffers from the same welding problems.

6061 hardens and is weldable, but will not give the yield strengths of 7075 and probably would not work for a frame unless thicker sections were used.

Interestingly some Scanadium alloys are weldable and some are not, but probably the weld will not be as strong as base metal.

Aluminum alloy is not as strong or flexible as steel and is much more apt to stress crack. Its main claim to fame is that it is about 1/3 the weight of steel. Titanium is also about 1/3 the weight of steel and nearly as strong, but. it will not take repeated flexing as well as steel. For flat out tough steel especially that alloyed with nickel is very hard to beat.

A pretty neat metal is aluminum bronze. Strong, good wear resistance, but it is heavy. Might make a WOW S&W frame.

I would love to be able to sent S&W a Damascus billet and have it forged and machine it into a frame (not the cylinder) and use a barrel liner. Be beautiful and strong. Real good Damascus barrels were not that week, but getting perfect forge welds using the process needed to make tubes was difficult. Then some cheap barrels were actually woven wire that was silver brazed.

1911 slides made from damascus look here:
damascus 1911 frame - Google Search

Actually the process for making Damascus steel has been lost in the mists of History. While we can make a product today that looks like Damascus steel in strict laboratory testing these samples do NOT match the performance of the real thing. BTW, learned that tidbit watching PBS, I think it was an episode of Secrets of the Dead.

Aluminum Bronze, that gave me a bit of a laugh. Because in the tube forming industry Ampco 18 and 21 are goto alloys used to make prototype swaging tools for expanding or reducing stainless steel tubing. Because Stainless steel will Gall nearly instantly if you try and use any hardened tool steel forming punch. BTW, Ampco 18 has a hardness of 18 on the Rockwell C scale and the much less common Ampco 21 has a hardness of 21 Rc. These levels of hardness means it's as strong as a non heat treated high carbon steel so it's quite strong. Also takes a beautiful polish if you spend the time doing it in stages, freshly polished it nearly imitates Gold.

As for welding aluminum, the biggest issue is that aluminum alloys are ALL returned to base "hardness" when heated to welding temperatures and can only be precipitation or work hardened. Common alloys such as 6061 are precipitation hardened and when first extruded quite soft but let it sit for weeks to months and in microscopic structure goes through a sort of crystallization process that results in it final strong state. Note, for mandrel bending we will usually request 6061 tubing in either T-1 or T-3 because T-6 will snap like a dry twig in a bend with a less than 2xDiameter bend radius. A big problem with 6061-T6 is that welding a structure together will result in welds that are basically T-0 state and T-0 Aluminum has a yield strength of only 11,000 psi. Note, IIRC t-6 Aluminum is around 30-40,000 psi yield. As for the 7075 Aluminum, at full strength it is actually somewhat stronger than low carbon mild steel, so forged Aluminum frames using 7075 alloys are pretty darned strong. Unfortunately as mentioned it doesn't weld at all easily or that well.

There is also the issue of welding any threaded part. Think about this. How would you get a thread tap started in EXACT registration with the existing tap that is "interrupted" by a weld bead? That more than any other reason is why you won't ever see a gunsmith or manufacturer offer to weld repair the barrel mount on any frame or receiver that is internally threaded. Another issue is the Heat Effected Zone adjacent to the actual weld bead. This area falls on each side of the actual weld and typically will be somewhat "depleated" in Carbon and as a result weaker than the base metal and the center of the weld bead. There is also the matter of the difference in the grain direction, expand welded steel tube and the weld does some very "interesting" things in the area of the weld. Typically it is sort of a hill peak at the center of the weld with two valleys on each side of the weld. Welds make a lot of products economically feasable but are NOT a good idea in an area subjected to high levels of stress and vibration, sooner or later they will fail and usually it's sooner. In the case of a S&W frame that failure will usually happen as soon as the barrel is tightened up fully.

Without giving you a lesson in metallurgy, the answer is no. It may be able to be welded, but it will never be fixed. Early aluminum/alloy frame revolvers were made before the makers knew any better. They are collectible and are to be shot sparingly. They do make nice paperweights.

...I must just be unlucky. My first 50s vintage 42 cracked... A Model 37 cracked and finally a Model 38....

Couple of years ago bought a mint used 642 that was not cracked...shot it once and just decided to sell it and ended up buying a LCR in 9mm...

Bob...who doesn't bother buying lottery tickets.

It would be nice if the factory offered a new frame to the customer with the same serial number as the old frame. Possibly offer it in steel also.

Great volume of info,,thanks for everyones posting.

FWIW, here's an interesting thread from Accurate Reloading on Bailey Bradshaw (TX) making up a damascus billit to use in the mfg of one of his double rifles. Forged and folded, forged and folded.... The hammer mill must be a real back saver!
Actually the entire rifle is built during the 5 or 6 page thread and is a good read w/ nice pics. Great stuff if you're in to 'projects'!
A little ancient craft, some high tech and some just plain fine gunsmithing work in the thread.

Damascus hornet double...in progress - Topic


There are a few that have made new damascus bbls by the old methods, those being in the muzzle loading trades. Both spiral wrapping around a mandrel & lengthwise forge welding the flattened damascus billit around a mandrel.
There's usually a few at the Dixon Gun Makers Fair in PA every year. They pride themselves on being able to actually make everything from scratch.
These generally use a coal fired forge instead of gas,,have to keep it old timey!

Scooter, if I were to attempt a repair on a steel frame I would make a brass piece with the correct threads and install it before making the weld. It MIGHT keep the weld area clean enough to start the tap to clean it up.
Would I do it to someone else gun? NO
Would I ever really trust the repair? NO

I guess you could also bevel the crack install the barrel timed and weld it up, never to be disassembled.

Mostly would do it for my own curiosity. Steel K frames are the most apt to crack and they are just not worth it for what they cost. Sell the parts and move on.

I have made a lot of modern damascus for knives.I have a bunch of billets made up in the shop, but have been distracted lately with S&W revolvers.

Eutectic aluminum alloy welding and soldering supplies have been used in the past to 'weld' Hi-Standard revolver trigger guards.
Of course they do not have threads or need to support the stress of the barrel being screwed in. But, it is perhaps a solution? These are relatively low temperature products. A "MAPP" torch without added oxygen sufficed..

I don't think so. I have seen that stuff used. Maybe better than actually welding one though. But, it was high strength alloy in the first place and failed. I would think anything less would also fail. But, its not like the gun would blow up, but the barrel might go down range.

I don't mind welding heavier normal aluminums over about 1/8" thick , I have a spoolgun and a tig torch, but small sections require a good high freq unit, a foot petal to control the torch and a cooling unit for the torch. ($$$$) and I am not that good with a tig torch, 2 hands and a foot at the same time, old dog new tricks etc. I do know some guys that are fantastic and have certs to weld most alloys to codes.

But, some stuff just will not weld well.

We used a lot of Ampco 18 and occasionally 21 for wear plates on dies in the auto industry. The plates were typically 1 inch thick and could range as small as a few inches square to 6" x 24" Typically, they were mated with hardened steel plates on the opposite wear surface. Some of these dies could be used millions of times, especially those used for sheetmetal panels that didn't show, like floor pans. GM's B car, which was the old style Bonneville, Impala, etc., were used for well over 25 million vehicles. The wear plates were used on the outer ends of the dies, to keep the dies aligned when the top half and bottom have came together to form a sheetmetal panel. Depending on the panel, there could be as many as 12 dies in a line. The first die, called a draw die, pulled the metal in to the shape of the panel. From there, additional dies added holes, folded flanges, added more shape, until the finished panel came off the line. One Cadillac hood die we had weighed in excess of 60 tons. Our largest press, also used for hood dies, was rated at 250 tons of pressure. If you paid attention, you could tell it was running from anywhere in the plant.

Getting back to the Ampco, wear plates had to be sized to fit, to make up for differences in machined surfaces. You would put the two halves of the die together with one set of wear plates mounted, then measure the space left between each plate and the machined area it's opposite plate mounted to. Then you either grind the opposite plate, if the measurement was under 1" or shim it out if the measurement was over an inch. No one liked to have to work on the Ampco plates, especially the 21. You didn't machine it as much as did controlled breakage. It would often chip off at the end of a cut, leaving a ragged edge. Grinding wasn't a lot better because it was non-magnetic and holding large pieces flat was difficult. Machinists definitely didn't like to see you show up with a piece of Ampco and a work order.

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So many S&W's, so few funds!!

I have a 4" round of it, was slicing it off in a band saw and using pieces to make guards and furniture on knives. Like stated very nice gold color that doesn't turn green like brass. Anyway it got to short to clamp well in saw so I took it to mill and tried a slitting saw. Mill didn't like that much. Even a parting tool on the lathe sucks. Good tough stuff, but not easy to machine if your making very heavy cuts.

No matter how unusual a cracked alloy revolver frame may be, I don't care. I avoid all of them, especially the Model 12, always have, always will. No point in taking any chances.

Ya'll saying Superglue won't work?

I bought a nickel plated M19 snub that had a cracked frame right under the forcing cone, weld repaired. The nickel plating was not factory original and an attempt to disguise the weld.

I sent pics to a Canadian S&W warranty shop who congratulated me on my "paper weight". Apparently it happens on steel framed guns not infrequently when barrels are removed.

I got my money back, the seller feigning ignorance.

No superglue, but, JB Weld should be good.