Ok,
my buddies gun is still here so....

Full .523
IM .528
M .536
IC .538
Cyl .542

rear diameter of chokes are between .555 and .559 measured with dial calipers. I screwed in the choke that measures .555 at the back, and the bore looks like it will be close to .542, given the size of the step.
I don't have a bore gauge here at the house.

Kind of wierd numbers.

Last edited by ithaca1; 07/30/16 05:13 PM.

Bill Johnson