I have two 556 ERs, one with an Eotech and one with a scope/bipod for shooting longer distances. I really like the new DMR with the rails, but wonder how the 1 in 10 twist rate 21" barrel would fare against the 1 in 7 twist rate 16" barrel I already have when using 75gr ammo. For a medium range shooter (2-300 yards), which would be more accurate with those heavier grain bullets? What I have read suggests that the 1 in 10 twist will not sufficiently stabilize a 75gr bullet. I would like to get others' thoughts/experiences with this issue before I decide whether or not to trade in on a DMR (if I can find one ...).