Originally Posted by RunningOnMT
My totally uneducated guess is that a 20" barrel might be just a tad more accurate than a 16" due to increased velocity. Increased velocity = less bullet drop over longer ranges because the faster bullet hits the target sooner. But that difference in velocity and it's corresponding effect on the POI would be so slight it would likely be imperceptible.
But I said that was a guess. For a real answer JLA is the man to tackle this question. He has spent many hours scientifically studying such things, and has corrected several misconceptions of mine regarding barrel/bullet mechanics.
A little more velocity does not make it more accurate, it's just slightly
I wonder why almost all 22 target ammo is lower velocity.
I tested the velocity of M193 ammo in a 16" and 20" AR with my chronograph and found an average of only 135 fps less out of the 16" barrel.
I'm talking real world shooting here, not extreme circumstances where there may be a slight difference that most shooters would never notice.
I'll step away from this discussion now and wait for those that know about this stuff.