The AK-47 varies in quality depending on the model that is used. I would prefer a high quality U.S.A. or Russian made 7.62 x 39 AK-103 over a 5.56 x 45 M-4. 7.62 x 39 from a 16 inch barrel is very deadly out to 250 meters in the hands of a good rifleman.
A bullet from a 5.56 x 45 AR-15 with a sixteen inch barrel loses much of its velocity by 150 meters. Getting hit by 5.56 millimeter round from 150 meters or beyond would be like being stabbed with an ice pick. The M-16 with a 20 inch barrel adds about 50 more meters of really effective range.
Army should upgrade our M-16 to fire the 6.8 x 43 round that way any of our soldiers could give really effective fire out to 300 meters despite having a 14 1/2 inch barrel.
If a new round isn't adopted the Unites States Army should at least adopt the new Mk262 Mod 1 77 grain round over our current 62 grain round. A heavier bullet means that a round will retain a high velocity out to a longer range.