You cannot get true "steel core" ammo for the 5.56x45mm.
M855 and loads using the SS109 "steel penetrator" bullet are a special case that the BATF has ruled to not be an AP round. The AP laws/regulations are setup specifically to deal with rounds for which handguns are readily available, for these cartridges which handguns are made the considerations are: special bullet design such as truncated cones coming to a sharp point, hardened metal cores comprising a certain percentage or making up that of the entire bullet, special coatings, or any one of a combination of those things.
Yes, there are 5.56x45mm handguns out there such as AR15 pistols, but the SS109 bullet is largely comprised of a lead core, the steel in the SS109 round doesn't really do diddly. True AP like the M995 round which has a tungsten core, now that would be a no-no.
M855 and loads using the SS109 "steel penetrator" bullet are a special case that the BATF has ruled to not be an AP round. The AP laws/regulations are setup specifically to deal with rounds for which handguns are readily available, for these cartridges which handguns are made the considerations are: special bullet design such as truncated cones coming to a sharp point, hardened metal cores comprising a certain percentage or making up that of the entire bullet, special coatings, or any one of a combination of those things.
Yes, there are 5.56x45mm handguns out there such as AR15 pistols, but the SS109 bullet is largely comprised of a lead core, the steel in the SS109 round doesn't really do diddly. True AP like the M995 round which has a tungsten core, now that would be a no-no.
