I had previously opined that BUL had never released the “official” factory mag sleeve for the BUL Impact. Apparently, this was not quite true, because a pair of 9mm BUL Impacts being auctioned off by Mach1Arsenal on Gunbroker have them:

These appear to work like the 3D-printed ones that I’m using – slip over the top of a full size magazine and just slide them down. There’s no locking mechanism at the top of the heel of the sleeve, which I had theorized might be a way of keeping it permanently connected to the grip. Unlike in the official shots, this sleeve doesn’t seem to be pinned to the bottom of the magazine. It looks to me like these sleeves are what would have been the bottom of the Impact’s grip if it were full-size.