How much do you want to spend?
My 12ga 1187 cantilever barrel is smooth with choke tubes. Even with a rifled tube, Nothing really shot better than the garden variety Foster slugs from Rem, Win, Federal, PMC, Rio, or Lee cast reloads. Killed a few deer with it. Missed and/or lost several too! My Rem 870 20ga rifled barrel w/sights was little better
I’ve now got a Mossberg M220. Wow!
It shoots 8” at 100yds with a Lyman cast sabot slug in AA-style wad over LongShot. Federal “economy” “PowerShok” 7/8oz sabot slugs shoot ~4” at 100yds. Killed several deer with them. All but one, DRT (dead, right THERE!). About $1.25each.... not too expensive, but only seasonaly available. (Not the common Foster style slugs, true .54”sabot slug.).
Finally, I splurged and bought some Remington AeroTip Sabot slugs. $12.95/5, plus TAX. Nearly $4.00 a shot. But, they shoot +/-2” groups at 100yds.
Now, if a deer will cooperate...
BTW, it “gags” on Hornady SST Sabot slugs. 2/5 keyholed at 50yds. Wouldn’t hit berm at 100yds. Buddies gun shoots them 3-4” at 100yds. Gave stash of Hornady’s to him. Also, not cheap...!