Tankers using the 20x main gun sight sometimes had the same problem with Infantry officers who saw nothing in their 7x binoculars. Neither did it hurt that we had a 52-ton bipood rest for our optics.
The XM-8.. when I was in uniform, i'd have killed to have something that was fairly light, could be turned and used quickly in brush, and had the ability to fire zillions of rounds in a pinch if I had to do so.
I saw relatively few 30-round magazines for the M16A1 during my 1968-70 tours, though a few adaptations from AK magazines were also around. We'd have happily settled for that.
I like the drum mag option, and the mini-203.
I'd also like all the above to be on an accurate rifle, wickedly accurate if possible.
But, I know I'm dreaming on that one.
For it to be accurate, light, and short enough for brush use, accuracy suffers from use of a shorter barrel.
Up to a point. But if you're in and out of a vehicle all day, or working from the confines of a bunker, or face other circumstances that make a shortyu barrel desirable, it's nice to know that there's a longer barrel capable of maybe twice the usable accuracy in your rucksack or footlocker if you care to swap it out.
And note that a shorter barrel that's thicker and more rigid is not itself necessarily less accurate, suffering less from the vibrations and *whip* of a longer tube, though velocity of the bullet from it will necessarily be lesser.