problem in RO shooting at a large group is the 1st row will stop most of the bullets with no penetration and by the time you aim for the empty parts to shot the guy in the back, hes already IS rifled you.
I was just thinking about this last night in DOD on flash map, or whatever that map is with the ruined railyard. I was german we advance to just before the last allied flag, and I set up my MG just as the enemy team,(7 of them on a 20 person server) came from respawn. They ran right across my field of fire.I got 4 right off the bat in a tight group, bullets penetrated the front 2 and hit the back 2. The last 3 scattered, no thoughts of ISing , got the next before he got to cover, got the 2nd to last just as he scrambled behind cover.
The best thing about Dod is no freaking corner clipping leaning, being plinked by a guys uppermost extreme helmet pixel doing the frikken limbo backwards while shooting. His choice of concealment was an old plaster wall. If DoD had the limbo shootiers they have the other only plus, that flimsy plaster wall I put a line of bullets across at ankle level then back across at waist. I would so love RO to have penetration, at least for MGs. 7 kills in about 2 seconds.