40 70 PP problem

[Kurt]

Ken.

Give us a little more information.
What is the brass your using?
Case neck wall thickness?
Chamber diameter at the neck. If you don't have this, what is the diameter of a fired unseized case mouth.
I have never seen Onion skin paper .005" thick.
A double wrap of your .005" thick paper would add .020" to your unpatched bullet.
Your .330" unpatched bullet would be patched .350" and that should fall right through your .403" bore diameter.
The .390" with .020" would be .410" diameter.