Ah, okay. I know the concept from AK mags, but didn't make the connection relative to the FAL since they hold open.Last Round Bolt Hold Open - bolt stays open after the last round is fired. The AKs don't have that, but Yugo mags do, though the bolt will close when the mag is removed.
Judging by the rest of your list, you're far more "well rounded" than I am. I used to own every one of the listed calibers, except for .223. Now I'm down to 9mm, 7.62x51 and 12ga. It just feels more manageable.
Augs and X95 Tavors. Yeah, baby!