I have the same problem with my 336.I live in Florida where humidity is always high.
Where exacty do you place the gasket material? Do you glue it,or leave it loose?
Does it matter which material to use?
I am full of lot's of things,questions are just one of them.
Dumbest thing I did (recently) was to try some 147FMJ Contender loads in my Marlin 30/30.
I loaded one in the tube,with the intention of one in the chamber as well.
Found out that the 147's were seated to long to clear the tube.
I had to push a cleaning rod down to "shorten" the round.
My buddy had a good laugh over this one. Who knew!
Thanks
Alan