[The_Victor]

From the forensics standpoint, would you be able to distinguish the difference between the 5.56mm and the .223 from the slug?

[mortarman]

From a recovered bullet, it would be impossible to verify whether it came from a 5.56mm or .223 cartridge. The rounds are interchangable. The .223 is governed by SAAMI specs, and the 5.56 by mil specs. The only difference is a different max pressure on the loading and a few thousandths of an inch tolerance in the chamber.