I got both the cleaner and the breech plug this week. Our deer season ends today (didn't want to shoot during season since our range in very close to some feeders & food plots), so hopefully I can get to the range soon and see if either change helps groups. I scrubbed the bore (didn't see any strips of plastic, but I did get a lot of black fouling and have been shooting black sabots ???). I plan to shoot one group with the old breech plug, then install the new breech plug and shoot another group.
I will post the results when I have the test completed!
Thanks to all who responded to the thread!