The steel cased works great in my 1919, and ak. However. In the ar it is crap for accuracy the projectile tumbles and about every 100 rounds or so a shell will stick in the chamber. Can't figure out if its swelling or the heat is gumming up the laquer on the shell. The brass monarch I've only tried the 3006 in my garand which was not bad for the cost, and its about the only ammo my springfield 1911 likes. And also no probs out of 500 rds in the thompson. I