JMHO but I suggest you atleast try Brenneke slugs. Either the 3" mags of 2-3/4" heavy field mags.
I won't bother with the "they aren't sabot" discussion. If Brenneke says they are good for rifled barrels then I'll believe it. They have been making slugs over 100 years and my guns rifling is just fine. The accuracy out of our H&R USHs is awesome.
And when you put a hit on a deer.......well that big, fat 1-3/8 oz. slug hits like a ton of bricks!