BudsGunShop.com - Winchester M855 5.56 ammo

This is a brass case, with a 55gr lead projectile, and in the center of the projectile is a Steel penetrator, this round is ideal for barrier penetration, and is highly effective against up to class 3A body armor, while it not technically an armor piercing round it will punch through most vests.
The green tip is for quick easy identification, because while the steel penetrator is good for barrier penatration, a regular soft tip, or hollow point can be more effective at stopping a threat when you don't have to punch through hard surface before hitting your target.

Steve, the M855 bullet has a copper jacket, lead rear core with a mild steel penetrator tip. The actual dissected bullet picture here : youtube.com/watch?v=PCfGKlArwZ8