The Colt Bushmaster are the two most often selected, and are very similar
differences include, but are not limited to:
Colt 1/7 barrel and 1/9 for BM.
The 1/7 allows a wider range of ammo including the heavier (more accurate ) stuff
The Colt has MP tested bolts and barrels, and the BM only randomly sampled -advantage Colt
M4 feed ramps on the Colts - Not sure about BM, I think not. More reliable feeding of ammo
Colt has double heat shield, large oval hand-guards, the BM has singles with CAR sized guards
Colt lifetime warranty. BM does not
The models for Colt are LE6920, 6721, and run $1,000- $1,350
and Bushmaster M4A3 Patrolman's Carbine runs $875 - $1,100
I would definitely go with a flat top (A3) to keep options open (Like your Aimpoint plans)
Even though Rock River has great stuff. The 2 above are the most popular choices
Good luck, hermes.......,welcome aboard and Happy New Year!!
ETA:
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