Full auto is about twice that rate of fire. Plus faster follow up shots. Plus much better ballistics. Speed is the largest variable in kinetic energy. 12 gauge buckshot is no joke, but I'd take the rifle caliber with faster rof and follow up shots any day!
OO buck is 9 pellets, .33 caliber, roughly equivalent to 9mm, per shell,
A Benelli M1 can get off 6 of those in roughly a second, which is 54 .33 caliber projectiles downrange in 1 sec. or less.
The rifle only offers a clear advantage when ranges extend beyond 70 yds, plus it requires aimed fire.