I just got to shoot a buddies 3-1/2" 20ga last night and it is a sweet shootn iron!!!!!!!! It is an H&R 980 in 20ga just with a 3-1/2" chamber. You can still shoot 2-3/4" and 3" and now 3-1/2" as well. The barrel and rounds are made by Hastings.
I saw this weapon previewed several years ago by a gun product developer/tester by the name of L.P. Brezny in one of the magazines I get. He developed the weapon to get a super velocity and energy round. He got it!! It propels a 15/16ths oz lead sabot round at 2000fps with 3800ft lbs of energy at the muzzle!!!!!!! Brezny took an American Bison with the prototype and shot it at approx. 150yds to only see the others mill around and his target animal just stand there to only just lower its head a bit. Upon watching for 20 minutes they approached the bison to find it was standing stone cold dead!!! Legs locked!!!
The owner, partner and son have take over 50 deer and have yet to shoot one twice. Only 3 have taken more than a step after being hit out to 187yds, with laser range finder, and none over 3 steps. Recoil out of the gun is like shooting 20 field rounds. He just bought a 3rd one and another 5 cases of rounds to last them all of their shooting days.