When I bought my first Encore, I went through about every load,sabot,powder,primer,combination you can imagine.
I finally found my best groups came from MMP sabots, 90 grains (loose) 777 powder, 240 grain Hornady XTP bullet, CCI primers, with packing pressure of 45 lbs.
Shot preparation is one wet patch (windex) and 2 dry patches, between shots.
Stay away from pellets if you want to shoot groups at the range. They are fine for hunting if you just want to hit a 4" circle on the side of a deer, but you are not going to get 1" groups at the range at 100 yards with them, normally. There are a few guns I have seen that will shoot well with them, but not very many.
The most important part of the combination is the sabot. Thompsons are picky about the sabots they shoot, and even their own Thompson sabots are not always the most accurate.
Your rifle will probably be fussy enough that you will have to play with a few different ones before you find exactly what it likes to eat.
As above poster mentioned, being consistent is everything with a smoke pole, so make sure you do everything exactly the same way, in the same order for the best results.