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PJR · January 20, 2001, 08:02 AM

There are few things more confusing than shotgun chokes. The standard interior dimension of a 12 gauge is .729" but I own guns that range from .723 up to .740 (due to backboring). The actual amount of choke constriction depends on the interior dimension of the barrel. The only way to determine the actual constriction is with a inside bore gauge.

Regardless, choke performance is the key and the only way to determine how your gun is shooting is to pattern it with the shells you intend to use. Shell selection can affect pattern as well. I currently have a gun that according to the chokes is IC and modified. However, on the patterning board it's closer to improved mod and full with my usual hunting loads.

January 20, 2001, 08:02 AM	#3
PJR Senior Member Join Date: May 31, 2000 Posts: 1,127	There are few things more confusing than shotgun chokes. The standard interior dimension of a 12 gauge is .729" but I own guns that range from .723 up to .740 (due to backboring). The actual amount of choke constriction depends on the interior dimension of the barrel. The only way to determine the actual constriction is with a inside bore gauge. Regardless, choke performance is the key and the only way to determine how your gun is shooting is to pattern it with the shells you intend to use. Shell selection can affect pattern as well. I currently have a gun that according to the chokes is IC and modified. However, on the patterning board it's closer to improved mod and full with my usual hunting loads.