I have a benelli m2 12 gauge with a factory 21 inch barrel. I run an Indian creek .665 and shoot 2 ounces of TSS #8. Average 310 #8 in the 10 inch ring at 40. Had it dipped and the receiver tapped for a vortex venom by Tad at Carolina hydrographics.
It is the best handling and pointing gun I own. My franchi affinity 3 12 gauge is a close second. My 11-87 compact 20 is Nearly as big and heave as the m2.
If I buy another 20 it will be a franchi affinity 3 and I'm having the barrel shortened by sumtoy.