I just picked up a new Bushmaster O.R.C. on Friday, and the mag that came with it looks identical to the 3 AR-Stoner mags I picked up, except the OEM mag has the new Grey Magul Genn II follower with CS spring, and the Stoners have the green follower, and all four of them look identical to the 4 C Products LLC mags I have on my desk right now with the Orange Magpul Gen II follower with CS spring. Other than the color of the followers, and the base plates they all look identical.
On a side note they are all Aluminum Magazine Body with grey moly coating.
And so far all fit the mag well, and drop free unassisted, and will lock in place on a closed bolt with 30 rounds in them. Other than that I cannot tell you how they feed as I have yet to get to have time off work to fire the thing.