Through my perusing for information on shotguns I have noticed quite a variety of ways to measure/describe chokes. I have heard references of half and full, 5/8 and 3/4, .693 and .709, 15 thou and 18 thou, and perhaps there are more. Some of these I understand and others only guess at what they mean in trying to interpret them.
My problem arises when the bores are not in proof and have been bored out. If in proof with a bore of .729 and a choke measurement of .693 I understand to be a full choke. However if the bore measures .735 and the choke .693 then what do I have in terminology of full, modified, etc? I also infer that to subtract these 2 numbers would be .036 and that by itself doesn't compute for me with out a common reference.
Has anyone compiled a reference chart of the different systems that reference back to a common denominator and/or a good description of how each system is measured?
Thanks,
David
