I tried the felt thing under a sabot, but saw no difference in the group. My Encore shoots about a 1" group at 100 yards, with or without them. When I first got the rifle, I tried about every kind of sabot and load that I could find, with every little trick, and I found that the rifle performs the best with an MMP black sabot with a 44 magnum Hornady Pistol bullet, at 240 grains, shooting 90 grains of loose 777, ignited by a Winchester 777 primer. I put 40 lbs of pressure on the rod, spit clean after every shot, and still get a flyer about one out of every 15 or 20 shots.
There is a good possibility that the flyer could be ME.