That's the EFMJ...expanding full metal jacket. I haven't tried it yet, but I've done some reading on EFMJ rounds and I'm considering using it in a limited basis. I'm considering adding it as either the round in the chamber and maybe the 1st round in the magazine, with the rest being my usual HP rounds. The EFMJ is, as best I can tell, superior to HPs in only 1 way...penetrating intermediate barriers. There's no cavity to fill with drywall/cloth/glass, so there's nothing to impede penetration.
I don't like how it shoots, personally. The ejection is haywire in my experience, and I experienced two jams in 200 rounds while shooting it. The Glock has never jammed prior to or after shooting the EFMJ.
