I get approximately 1" groups with 2 pyrodex pellets, hornady sabot and 240 grain XTP. Did not get good accuracy with three pellets.
I also clean between shots with a spit patch, dry patch, and then a patch lightly lubed with bore butter.
I have teflon washers under the forearm. Don't remember if they helped in the accuracy department, but the closer to a free-floated barrel the better.