New Army "Caliber Configuration Study"

[BluntForceTrauma]

M2 AP was designed as armor piercing, but was adopted by the troops as general-purpose because of its penetration performance on a variety of barriers. If one wants to specify an AP round as a general-purpose round, I'm cool with that. I'd probably be happy with a copper and carbide steel GP round.

There are many 7.62x54R bullets. Which one is the mild-steel core load, the standard PKM load, to which we should compare?

Regarding your point that a lead-free bullet, by virtue of its length, has a higher BC, is something I didn't realize. Could be my understanding of ballistics is shaky (ping pong balls vs golf balls?). I thought material density also factored into BC, in the sense that if form factors are equal, the bullet with a higher material density has a better BC. Conversely, a bullet of a lesser density needs to be longer to have the same BC as a bullet of higher density. This is why I postulated that a 108gr lead-free bullet in the 65G case might be too long to be practical to match 7.62x54R.

John