Underclocked is right on..

I have been giving the breech plugs of mine two wraps of white Teflon tape, then with a model builder's paint brush I paint a nice thin coat of anti seize onto the threads. I screw that in just finger tight. I still get a little blow back, but I live with it.

Swab the barrel between shots. Put a loading jag on the end of your range rod. Work a lightly damp patch in short strokes down the bore to the breech of the rifle. Then pull that and reverse the patch and do it all over again. Then a couple of dry patches and you should be set to fire. Do not worry about that gray stuff down by the breech plug,it will blow out with the next shot.

A good swabbing solution is Windex or car windshield washer fluid and alcohol mixed 50/50. There is no need to pull that plug until your done for the day.