I got a bit of time to pull the bullets and weigh and measure them. Of course, this is just a sample of one each but the suspected AP round weighed in at exactly 144 gr and the other at 143.5. The 'AP' round was also .01" longer from the base of the bullet to the ogive.
Assuming those discrepancies would hold over a larger sample, they are definitely different somehow (although I don't know the tolerances on mil-spec ammo).
I couldn't find a strong enough magnet to test at home so I'll try work tomorrow.
Instead of cheesing out our plates we'll just save that ammo for really tough stuff--you know, clay pigeons!
P.S. I'll have to chrono these out of curiosity to see what they're running. Both cases had 44.0 gr of what looked like RL15.
