If you have a smooth bore barrel ,try Brenneki KO slugs .

I get groups out of my 11-87 smooth bore barrel that are better than many rifled barrels and saboted slugs.

I checked zero last weekend and had a 1.9" group at 50 yds and 3.5" group at 100 yds (average of 3 , 5 shot groups )
I had 1 group where all 5 touched and produced a 2" group at 100 yds

Sand bags and a Red dot sure help

Johnch