The listed effective ranges between the m16 and AR are misleading at best and flat out wrong.
Claiming the AR15 round is "devastating" is funny/sad considering the rifle is available in a plethora of chamberings, all with different velocities and pounds per square inch. Cant hunt game with it up here because its unethical. But yeah, it shoots coke cans.
Never mind a slower round out of a shorter barrel, IE customizing.
NewEra, the m14 and m1a is not an incredibly accurate rifle. Baseline for an acceptable rack grade rifle for the US military was 7 moa. Minute of pie plate. Chasing accuracy out of that platform requires specific knowledge and deep pockets. Kick like a mule is not how I would describe it at all, not even close. Far less kick than the same round out of grandadddies m700 bolt.