I've never found BBs in the litterbox, thankfully. Little bastard likes to eat everything though, so I'm honestly surprised. He likes to chase little parts around when I've got my guns disassembled and spread out on my desk on a cloth.
There's been the odd time I've shot off a spring or something like it and had him bring it back to me, though, so there's that.
He's a cute little fucker, though.