All of my BP's are concave faced, I have been unaware of the problems of concove vs flat faced BP's.

If it were me and you were going to try my suggestion, because I would really hate to lead you astray - Do as Cayugad suggested also. Put the tape on press it down on the face of the BP and install the plug snug, not overly-tight, just enough to insure compression of the tape,- I actually use a socket and extension. Then pop a cap or primer to clear the flash hole. Shoot 4/5 rounds - loosen the plug and if it moves back with a small amount of pressure re-tighten it again and continue shooting. You might be able to do this a few times before you destroy the tape. If you do not compress the tape to the point of tearing you might be able to this several times.

As Cayugad says, "if it isn't broke don't fix it" But I think you might have great success if you stop those gases from coming back through the threads. The tape and the threads being tight to each other seems to solve this problem for me. If you are able to see the pictures of my Remington breech plug you can see the condition of the tape after several shots. I have great confidence in this method but it took me several years to really trust it plus I was trying all the new stuff. You will eventually create your own.

The tape serves another purpose for me in that I never have to worry about grease/oil contamination of the powder and with t7 you don't want anything in the country that might have moisture attached with it.

In the Remington's I am shooting 100 grains of t7 and in the A&H I am shooting 110 so it is not like I am shooting a weak loads either.

Best of luck in you endevors...