Yesterday when I was sorting ammo, I found about 20-30 rounds of this federal .223 with an unusual bullet. I'd like to know what it is, but I don't have a box. The case is nickel The bullet is a uniform dark gray The headstamp is FC 223 REM It may be a tactical or law enforcement specialty load. I can't find anything that looks like this on federal ammunition's web site. I am sure this is factory ammo. Anybody got a clue?