I remain convinced that short barrel and all, putting a scope on the M4 would go most of the way towards matching the M16 at a distance.
Miles ahead of you. Special Ops units mostly put a Trijicon 4X ACOG on their weapons, as do an increasing number of just-plain-infantry folks. Check the photos. The Trijicon has a tritium-illuminated reticle. It's a good solid scope which can take an incredible beating (I know. I gave it one) and hold zero. It's very lightweight, too. Of course, the M4, M4A1, and M16A4 can all accept any rail-mounting scope, but the ACOG is issue.
And yes, you can hit men at 500 yards with an M4A1 and ACOG.
For CQB the EoTech holographic sight is popular.
d.o.l.
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