Eventually I went to deer hunting w sabot slugs (WW High Impact Supreme 2 3/4") in a 3" Remington made rifle sighted bbl (fully rifled).
Drilled and tapped my receiver, slapped a 4X Leupold compact on it (had high comb stock). It was dynamite.
I had a Mossberg 835 well before that, 3.5" chamber on the rifled bbl. It shot like crap, was rougher than a cob.
Cantilever didn't converge w bore, so ran out of scope adj, had to pop scope off and bend cantilever (eh, it happens).
Blew a good chunk of $ before realizing that though.
Gun got bore polished some, but it still shot sabot slugs of various manufacture (2 3/4" and 3") like total dog crap.
I suspect the jump due to 3.5" chamber was messing them up.
Was able to zero it w 3" WW 1 oz fosters and took 3 deer with it over the next couple yrs (90, 165 and 35 yards).
To get that POS Mosssberg zeroed, it took 2 days and I fired 90 slugs from the bench (testing ammo, cleaning intervals, foulers etc).
IMHO the only Mossberg deer gun to have is an old smoothbore 500. As far as smoothbores go, they shot pretty decent and usually whipped Remington smoothbores. Thick wristed, they suck with field stocks and bird barrels. But the clunkiness is tolerable in a deer gun.
I went Remington after that ^%$#@ 835 and never looked back.
BTW, when Remington did their 3.5" supermag 870 combos, the deer barrels were 3" chamber, not 3.5". Heck i think the only 3.5" slug back then was Lightfield.
