I'm trying to decide on which of these rifles to buy; I've got the 6721 on order, but I'm thinking of changing to the either the 6920 for better reliability or the 6520 for less weight; maybe I'm off the mark, so I wanted to ask you guys as I'm not really up to speed with the Colt products.
The 6920 is the M4, right? So it has the 1:7 twist which will not be as accurate as the 1:9 twist on the other models, but it is the only one with the double heat shields, and (correct me if I am wrong) the M4 ramps cut into the upper itself? Is there any REAL improvement in this upper from a feed reliability perspective, and is there any REAL degradation of accuracy due to 55grn ammo in the 1:7 twist?
The 6721 is the heavy barrel, and the 6520 is the light barrel, and both have 1:9 twist, chrome-lined barrels, correct? And Colt is the only manufacturer out there with the light barrel contour right now, correct?
Thanks for the assist-