I agree with JD as he agrees with jr. "Handy" Larry? There's a "test tube" rack at our club skeet range with about three of these step gauges. Galazan didn't invent the darn things. I think ours were turned by Brent Warner. The skeet "Nazi" doesn't understand; he wants to stick the damn things in every barrel that comes down the pike. Repeat after me: .729" is fine (and appropriate diameters for other gauges)" but it's not mine.
The phrase that clears out the confusion (except for the skeet Nazi)is "points of constriction". Constriction is getting tighter as in "choking". Points is thousandths of an inch. Constriction is ALWAYS measured relative to the major bore diameter. It does not yield an ABSOLUTE measurement wall to wall in the choke area! Those who persist in Ass U Me-ing otherwise are tedious in their refusal to learn. The I.D. of your choked area is X thousandths less than the I.D. of your bore. That's the bore of a particular barrel of YOUR gun; not someone else's gun or an accepted standard ("nominal" bore size for a particular gauge.
jack
