DKConfig turned this photo up. Identified as a S&B Paintball cartridge, but S&B has never made paintball rounds as far as I know, and I’ve looked at a lot of S&B loads over the last 6 years of attending the Czech meeting. This round was never mentioned. I suspect it is a load in an S&B case.
The bullet looks kinda familiar to me, but I can’t place it. Maybe one of you guys who still have functioning gray matter can help.