My M2/Carlson .580/Fed HWT #7's combo is the ticket if range is likely to be beyond 30 yds. If 30 yd. or less then Benelli factory full is about the perfect pattern! A quick comparison between my Fed HWT 1.5 oz. of #7's (335 pellet count, out-penetrate lead #5's at any range) and my buddy's 3.5 in. 12 ga. with 2.25 oz. of lead #4's (305 pellet count) tells an interesting story of technological progress.
P.S. I had the good fortune of seeing the above Carlson combo's long-range pattern etched into a dew-covered crop of spring wheat a few weeks ago (behind a turkey's head). I could not get over the lack of increase in pattern width as the load travelled out many, many yards beyond expected shooting range. That Flight-Control wad sure holds it all together over extended distances. Try it yourself and see.