Yes, you are confusing exit diameter with choke constriction. For a bore that measures .730", a choke with an exit diameter of .665" has a constriction of .065" (.730-.665=.065). A choke with an exit diameter of .650" has a constriction of .080" (.730-.650=.080). So a .650 is tighter than a .665. These numbers are for a 12 ga, but the same principle holds true for all gauges.