The 340PD is a .357 J-frame. During qual 5 rds of 38 +P 135 gr HP Gold Dot SB. Chunk that came off hit the instructor running the course (no injury). Low round count, just carried a lot in an ankle rig. It continued to run after the chunk came off (round 2 or 3 of 5) as the shooter did not notice it.
Attachment 255706Attachment 255707
Apparent cracking initiated by notch sensitivity. Failure crack most likely originated from a tool mark left over from broaching the cylinder recess in the frame. S&W would be well advised to increase the filet radius as well as improving surface finish in the filet and/or shot peening. Looking at the brown stain adjacent fracture looks familiar, this appears to have been working a while and picked this time to let go.
Cop armorer friend in SoCal had to send 2 or 3 standard aluminum J frames (642/442) back to S&W that cracked the frame at 6 O’Clock below the forcing cone. S&W said that happens sometimes from hoop stress transferred through the aluminum when the machine screws on the barrel or when they thread the frame for the barrel. They replaced the entire gun each time.
The so-called S&W "lifetime warranty" has limitations. Same retired LE armorer bought himself a retirement-gift all steel 640 and the “hammer stud” broke off flush with the frame with a few hundred rounds on board. From the gitgo dry firing it did not feel quite right, but was still working as the side plate kind of holds the stud (pin) in place...When he popped off the side plate he saw the internal parts slightly shifted...well that’s not normal.
For a number of reasons I won’t get into S&W needed to replace the frame (they can’t repair aluminum frames so those are replaced when this happens) they sent him a bill for $145 even though they said it had nothing to do with anything he had done. I had to get the local S&W LE rep involved and even he could not explain why this fell outside the normal “lifetime” warranty. Somehow he eventually made the bill go away. Those without a badge or retired credential probably won't be as lucky.
Attachment 255708
A broken hammer stud is becoming more common with the shift to MIM. Especially on the N frames. Machinist buddy fixes a lot of them because guys don’t want to wait 30-60 days for S&W “service”. As for screwing on barrels, they sure torque'em on tight. Forcing cone constriction has been a problem with the late production guns I’ve inspected. It's usually $100 gunsmith fix to set back and refit, but shouldn’t be necessary if they fitted correctly just cut a UNF-Class 2A thread, not a 3A, then just screw it in correctly and pin it, Like they did in the old days. One of many reasons I prefer the older revolvers. That stud as now manufactured is now a MIM part press fit into a slightly raised collar instead of being screwed into the frame. The repair is to drill it out and then tap thread the frame and install a new stud the old fashioned way.
Reinforces my gut instinct that "an old gun that works is worth more than a new gun that doesn't."
None of my older (1970s) S&W Model 12 Airweight M&P .38 Specials have failed firing standard pressure (NOT +P!) loads.
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Originally Posted by BK7saum
