By "AR10" I mean a 7.62x51 AR weapon.

Let's say criteria are accuracy, weight, and durability/reliability. Not saying it has to be a dedicated sniper weapon like the SR-25/M110, but more like the Armalite AR10 "Infantry Rifle" (with a flattop receiver for RDS/magnified optics). Obviously not suggesting Armalite is in the competition quality-wise, but something along the lines of a scaled-up M4. For 7.62 I'm talking an 18" or 20" barrel, not a 16" or less.

I ask this on an AR-based website, so I know what the general consensus will be. Yet folks on here usually do a pretty good of being honest.

Personally I think that the perfect platform for a 5.56mm combat weapon is the AR (at this time in history of course). What would be the perfect platform for a 7.62NATO combat weapon?