Myself, i have never shot the Thor. My experience was using 500g conical. They wouldn't shoot in my Omega X7 worth a darn. At 47 yard 5 shots made a shotgun pattern. So.................i cut the QLA off. That made all the difference.
Then i gave the very same 500g conical a try at 100 yard. That group was about 2" if i recall correctly. Removing the QLA was quck and easy, and was done without any fancy tool. I suppose the correct way to do it would be to cut into the rifling, but i hoped i could leave about 1/16" of the QLA, and have that work; it did.
At any rate, it didn't cost me anything, and now my rifle shoots them conical.
Semisane wrote a thread about removing the QLA, that i used as a reference. His technique of using the tubing cutter to mark the cut virtually insures the final result will be square. His job was far prettier than mine; i didn't take near the time he did, but i did end up with an accurate shooter.
My guess is the QLA is the problem with the Encore shooting conical, and removing it will result in your rifle being a good conical shooter. The Hornady FPB bullet shot pretty good, even with the QLA, so they may be another option.