Do you tape instead of greasing the plug?
I'm new to muzzle loaders
Ya know... I actually answered this a little earlier got it already to post - and pushed the wrong dang button - gone all gone.
So here we go again...
I do tape instead greasing. I started greasing at first and swiched right after to tape at the suggestion of another forum member - Underclocked. He suggested the tape.
One thing also after many years of doing this - I also believe the BP should be turned in and seated snug - not really tight but snug... Snug enough to squeeze the tape but not so tight to crush or tear it. Finger tight or backed out a bit is does not work for me...
This drawing done for me by underclocked with my explanation might help you understand what I am trying to say...

I really believe if you get the face of the breech snug against the shelf in the barrel blow by gasses will be stopped there and not reach the threads of the BP or Barrel. If you look down the bore with a pin light you will see the shelf that I am referring to. It is important that this shelf be cleaned of carbon and grease. nice and shiny just like the end of your BP...
Here is a picture you can see the shelf and the fact it still needs to be cleaned... you can see in the bootom pictures where I flushed it off.

Teflon taping a plug... There is a method and it really does take some time to perfectthe wrap unless you are a plumber... they can do it in their sleep.
Here are couple of pictures that show the wrapping process... Make SURE you overwrap the nose of the plug then push it down over the nose and into the flash hole cavity.


Wrapping the plug - you see two different colors of tape. The pink tape is a little thicker than the white tape and really prefer to use the pink tape, but you gun will detirmine that depending how tight the plug is or fits in the breech plug port in the barrel. One key when turning the tape in is that it turns in easy and smoothly. Make sure to press the tape into the treads of the breech plug so when you are turning it in the port threads so not tear and cause the tape to pull and ball up. To help this you may have to clean the old carbon and grease from the port threads. Cleaning them once and using tape will make it so you should not have to clean them very often again.
After all of this if you are going to try this method it would be my suggestion that after you have taped the plug apply a very light coat of grease to the outside of the tape. Then at the range loosen the or just barely "crack" the BP after 10 or 15 shots. If you choose to go with bare teflon - crack the plug after 5-7 shots and re-snug it.
At this point I just wrap and shoot.... on a few occasions when I do not get the plug in just right it does get hard to realease after 30-40 shots. Also you can check your job after installing by shining the pin light down the barrel and see if yu see tape all the way around the bottom of the bore.
Ask more questions if my explanation is not clear - I am not the best writer or written explainer in the world...
mike