"Seat the sabot to a marked spot on the ram rod."

Thismay be your problem. APP and JSG like to be compressed. The same is true of granular 777 and Pyrodex to a lesser extent.

When using the 777 and Pyrodex pelletsyou can feel when the sabot contacts the pellets-stop.

For granular powder: Get yourself a 2" furniture knob and drill a hole in it for the ramrod. Put it on the end of the ramrod and lean on it when seating the bullet. Try 120 grains of JSG granular and give the 250 grain SST a try as well. My Encore shoots very small groups with this combination.

Good luck with your Encore.