I agree with the advice already given:
1. Ditch the pellets and switch to loose powder. I have no issue with using T7, but I absolutely have to swab between shots to get decent accuracy. In your situation where you have a possible second shot, when maybe switch to BH209 instead. Then you can probably eliminate the swabbing between shots and still get same POI.
2. If that is your original breech plug you may need a replacement. I am surprised how fast my breech plugs erode.
3. The 250 Barnes TMZ is a great bullet and very accurate out of my Omega and Knights. Sometimes I've switched the Barnes yellow factory sabot for the Harvester Crush Rib yellow (also for boat tail bullets).
Good Luck... Rob