I have the necessary tooling to modify my original CVA breech plug (I purchased and installed a BH209 plug).
What size hole do you put in the face and the depth and also what type screw do you use for the vent liner?
The original plug is sitting in a box of ML parts so it doesn't matter too much if I mess up.
If i understand the question, the hole is about 3/8" deep, and is a strong 3/8" diameter. For vent liners i use
Holo-Krome screws.
This thread shows one way to modify the QRBP.
This thread shows one way to make vent liners.