[El Gato]

The M-4 is just a tarted up M16 with shorter barrel. Same round and the same problems from a ballistics standpoint.

Worse actually. The round has lower muzzle velocity when fired from the shorter barrel of the M-4, and more often fails to perform the proper terminal ballistic manuever, ie yaw.

[ctdonath2]

That has been addressed by improved ammunition. Mk262 77gr ammo reportedly works very nicely from the shorter barrel.