30cal Crown Air Stripper ID

Well Jimmy the .30 cal pellets' true measurement is 7.62mm, so my advice is to increase the size to 8.729mm (.3437")...which would be an 11/32" drill size. This would give you .5545mm of clearance on either side of the pellet as it passes through, which should preclude any possibility of clipping. 

The stripper measures 8.2mm, .323"

You have a golden opportunity here to make it smaller, thus quieter, then Factory because you can tune it to just at the point where it doesn't clip. Just something to consider. There are a lot of stacked tolerances between the barrel and the crown shroud.....

I usually go .5mm above bore size for air strippers.

The exit hole on my Crown's moderator is 0.355 inches.

James