backinblack
NES Member
Have an extra illuminated scope lying around that I think I want to build a non-223/556 upper for. What higher power cartridges fit in a standard metal mag without having to cut anything or bend up feed lips? Have a bunch of "pre-ban" standard capacity mags that I want to utilize and not damage... Was thinking vanilla 300 blk, however I'm not sure it's much of an "upgraded" caliber, and I think I've read somewhere that the 6.8 rounds require cutting and/or bending... Suggestions?