Requirements for Replacement of Currently Issued 5.56 M-855 and 7.62 M-80.

[RedFalconBill]

If we could get the 6x35 to shoot it's 65gr projectiles at 2900fps out of a 14.5" or 16" barrel, that would be nice, and could initiate the replacement for 5.56 NATO.

There is no way for the 6x35 (aka 6mm Whisper and 6mm-221 Fireball) can get those types of velocities. You would need the 6x45 and an 18", or longer, barrel. Since the 65gr 0.243" bullet has the same SD as a 55gr 0.224" bullet, just how much better will a 65gr 0.243" bullet @ 2,900 fps be than a 55gr 0.224" bullet @3,200fps?

I also have not chrono'ed many M-855 rounds, that when fired out of an M-4, go much faster than 2,900 fps, let alone 2,950 fps. The bulk of the ammo has averaged 2,890 fps +/- 30 fps.