ronlaughlin

That 30 degree angle will work... it is a lot nicer to have the 40 degree - but the last one I did I did, was with the drill bit as you are thinking. When you install the vent liner - you will use BP grease on the threads and under the hood of the vent liner. Snug the liner up and compress the grease. I shot 30 rounds the other day with a Knight (T7), removed the breech plug and un-screwed the vent liner no problem.

Other alternative - take the bit to a machinist and have him change the angle for you.. he can do it in a hurry.