I'd say your barrel is the "correct" one for a flatgate, as obviously a 7/32 " ( .21975) will drop in your gun, , I use a number #2 drill for the later .mag barrels as it is .2210", and approximates the 'land' size ,not the groove. Not sure of the "exact" sizes, "lands, and groves",as the "nominal" bore diameter is .222" for the 22 lr and .224" for the magnums...........but as street noted the barrels with the "Inc" or the adjustable sights SC's, the #2 drill "fits" and will NOT go in to the early flatgates, not even close....just for "grins & giggles" I tried a few laying around here to verify this.........