The M855 (SS109) I have in 5.56 is AP ammo. Sort of...
I bought a case for ####s and giggles and as soon as I got it home I pulled the bullet out of the case then used a side cutter to see what the steel core was like.
In my case, the penetrator is a hard steel tip underneath the copper jacket. In this caliber, I read on wikipedia that the goal was to have .223 penetrate steel helmets at 400 yards.
Shooting at a 1" steel gong at the range doesn't produce much of anything. A small dimple in the steel is all I get. (Very small)
The .308 pic posted early in this thread is not like the m855. I have a large lead core with a small steel tip. Does .308 come the other way around with a large steel core with a small lead tip?