Paul, your experience of sending the gun to S&W and then finding that the problems went away says it all, for me. I claim no expertise, only lots of experience.
My experience with magazines has been that they work or they don't. If they don't, i never spent the time, money and energy to try to get them to work. Take 'em apart for parts or pitch 'em. Worked every time.
Again, my narrow range of experience: break-in used to be necessary for new guns (30 years ago and more), or anything that was custom or modified. More important for target shooters than defensive shooters. For off-the-shelf guns, if it wasn't "broken in" by 200 rounds (50 being more like it), back to the armorer or manufacturer. Any semi-auto that choked on more than one magazine always meant a gun problem, so back to the armorer or MFR. I was taught that any gun to be used for defense should be fired with the ammo expected to be used until the user feels it is reliable and accurate. No number specified, but I stand by the 50/200 rule, above.
Limp wristing. I've seen people who experience jam after jam with a gun that everyone else had no trouble with.
An armorer showed me a valuable lesson I have used many times since. It doesn't answer any questions, but, in my opinion (and that of the armorer) it tosses any explanation for LW out the window.
He took a bone stock Colt Series 70 and put two rounds in the mag. He chambered one. Then he turned the gun over in his hand, using his little finger to pull the trigger with his thumb holding the grip safety, and his fore- and middle-finger on the front of the grip. No gun he ever tried that with failed to chamber the second round. He tried it with my well-worn military-issue Colt 1911A1 and battered, soft-sprung magazines, with the same results.
I've done it countless times since, often with a gun the shooter was allegedly "limp wristing." I'd take the jammed gun from him, reload the magazine if necessary, chamber a round and shoot strong and weak hand. Never saw a sound gun fail to chamber the next round even when I held it very loosely.
One guy came to me with his shiny new Beretta 92, a gun he bought because it was identical to the M9 he was issued in his active-duty post. It would jam for him at least once in every 10 - 15 rounds. A little more than once per magazine. I did the same thing with it. No jams. I handed him my Glock 17, a gun that had never hiccuped for me. He experienced jams right off the bat.
Meaning absolutely nothing, I have come to classify this the same way I learned to classify people who might get airsick. Some will be fine even if the plane flip-flops and cuts di-does all day, and others get sick while standing in a moderate breeze.
I don't know what "limp wristing" is, but it seems to me that a person either has this undefinable problem, or does not.
