ORIGINAL: Roskoe
.223 A.P. ammo most likely has a military designation of SS109 or M855 - and should have a green tip. The bullet will be a 62 grain boat-tail with a two piece core - back half is lead and front half is steel. Check it with a magnet to be sure.
As for armor piercing capabilities both the M855 and SS109 has no better armor peircing capabilty then say a soft point 30-30 or 308.
also i have never heard anything about military surplus ammo having the powder removed then reassembled with new powder to be legal to sell. You can buy surplus lake city SS109 which is the same exact ammo our armed forces use. the only ammo ive heard of the old powder being removed then new powder added was WWII era 50 BMG. most likely because it was machine gun ammo and would be to hot to fire in a barret or other forms of shoulder mounted rifles.