I agree the "green" tip is probably Armor Piercing. The belted ammo is standard 4 and 1 ball and tracer.
I guess I'd have to ask WHY would you shoot this stuff? As RC Model says, it's definitely corrosive primed. When I was a young Private, we would fire up the immersion heaters, and heat several garbage cans full of boiling water. We'd strip our M1s down all the way, wash all the parts in boiling water, and pump boiling water through the bores after shooting corrosive ammo.
That's too much trouble just for a couple of dozen rounds.