I shoot an Ithica Deerslayer II in 20 gauge with a fully rifled barrel and love it. I shoot lightfields through it and the accuracy is great. They have gone out of business though and been rebought so I have no idea of quality and what they make anymore. I have also heard great things about the H&R.

I would recommend a 12 ga with a slub barrel, using hornady rifled slugs. they aren't like normal slugs. they almost look like a muzzleloader bullet in a shotgun casing.

Called Sabots! (say-bow)

I much prefer the 20. A flatter trajectory and plenty of punch to take down any whitetail. Also a lot more fun to take to the range. I am 6'2" and 200# and I do not find it fun to shoot the 12 at the range after a dozen shots. If you are not recoil sensitive at all go with a 12 but I see no advantage but more ruined meat. Just my .02$.

Ditto on the 20 gauge fletch. i have an 870 express 20 and i love it. i shoot 2 3/4" winchester super x's and next year i am switching to the new 3" versions they are gonna start making. i can shoot consistently without a scope to 40 yards which is perfect for the areas that i hunt.

My pick would be an automatic with a rifled slug barrel .I use a berretta 12 ga with a hastings barrel & scope & i have no problem putting 1.5 " groups at 150 yards using hornady sst slugs . I have hunted my whole life with a pumpkin slinger go with the 12 ga trust me i dont believe a 20 has enough knock down power at farther distances ,it took me several year to talk my dad into a 12 & he said now he would not go back he uses a browning gold hunter ,both are great guns.

I bought a Remington 870 with a rifled barrel this year. I use lightfields and I can shoot accurate up to 150 yards.