M4: we're shooting the 55 grain. I've got a case of it sitting in front of me right now. It's marked M193, FMJ (copper jacketed). Beautifully polished brass. Boxer primed. Head stamp is "S&B * .223 REM", where the "*" is some funny little maker's mark. It comes in glossy light green boxes of 20. Lot code is 303/3. Packaging is top notch, not amateurish.
Grock: I saw that thread. I don't know where they got that crap from, or how old it was, but holy shit, firing dented cases! That's nuts!
An interesting thread, but it must have been some old ammo, because it just doesn't jibe. It's not the same stuff we've been shooting, that's for sure.
BTW, we also go through an even larger volume of S&B handgun ammo, all major calibers including .40. At least twice as much. For example, we just hosted the Farnam advanced course. 20 people shot over 14,000 rounds in two days, almost all of it S&B, and without a single problem. Most of it was .40.
So sure, watch out for old, crappy, surplus S&B, but I wouldn't stand on ceremony and blow big bucks on Federal just because there used to be problems. It's good stuff these days. I hope it stays that way, because I can afford to shoot a lot more often with it.