I am also a believer that the breech plug should be snug in the barrel... The reason for this is the face of the breech plug should mate up with the shelf in the barrel and create a gas seal at this point. If you can get the seal here it protects your threads...
This drawing is an attempt to explain what I am saying...

In the drawing you can see I suggest using teflon tape to create the seal both at the two mating surfaces and the threads if the gas should leak by the first seal. At lot of people use grease to accomplish the same thing and it works for you great. I just never have like the mess and the tape seems to me easier to use. BUT... it doestake some practice to apply it correctly. I would like to say it is 100% effective but even at times I still get a leak once in awhile that results in a very tight plug to start to remove but once moving it turns out easily...
This was one of my first attempts to explain the taping method...

This is the re-dooo, and you can see in this picture set I am using white tape versus the pink tape in the first picture. Pink is a little thicker tape and seals a bit better but some plugs are to tight to use pink.

If you decide to try this taping method I would suggest that you put a small amount of grease on the outside the tape until you build confidence in the application.
When you remove the plug most of the tape will remain in the BP orfice and you will need a bore brush to pull it out...