While I was busy trying to get a decent load for our S&W m&p .223 I grabbed a bunch of Wolf steel case ammo.
Twins shot up a few rounds and then the rifle jammed, bolt stuck. Took two of us, a BIG screwdriver, and 30 minutes of sweat to clear the fired case.
Upon examination of the throat I found half-moon pieces of steel. Some of them were jamming in the bolt, locking the bolt in place. What a freaking mess to clean.
I have quite a few pieces of brass from various manufacturers and not a single one exhibits this problem.
IMO, STAY CLEAR of the steel case ammo.