Works FLAWLESSLY, as long as you have the Borebuddy/CMMG style bolt and the mags for last round hold open. Those 31 round Gen 2 Black Dog Magazines work very well with this at making it run just like an AR 15. It works well for manually holding the bolt open, also, it does work with the MAGPUL BAD lever. Its workable with mags without the last hold open tab. If you have run the Gen 1 Black Dog mags or the Gen 1 CMMG mags, you know exactly what I am talking about but least you can lock the bolt open now, manually, before the next mag then drop the bolt on the fresh mag. Did try to get this to work with a BCA 22LR upper with some not so stellar results, it does hold the bolt open like its supposed to with a BCA 22 bolt but catches the bolt on release, slowing the bolt enough to not always slam home consistently, usually doesn’t happen on the first round but always seems to hang up on the second, after you fire the first round. Considering its not designed to work with the BCA bolt, the fact it somewhat works and could probably be made to work with some modifications, is a hell of a pro! Overall, if you have a dedicated 22 upper with a Borebuddy/CMMG bolt for your AR15, you should have one of these in a lower
