Bore Gauge questions

[Andy]

Hi folks.. Just received my Gary Bulley 10-12-16 bore gauge. Damn what a great guy and product and price. Now for my stupidity to show, since this is new. I have 15-20 pieces to measure but want to be clear about something.

I have the 18" dial model and insert to get the bore reading, then pull out looking at the amount of constriction.

First question is, if "nominal" diameter is .662 (16g) and I get .665 or something, is that usually from boring out, or are Parkers pretty much consistent in their stated diameters? I have other guns to measure too.

Second, when measuring the choke, do I take the gauge ALL THE WAY until the little bearings are ready to come out? The reason I ask is that I'm surprised how much constriction one of my guns has. Going from .10 to .22! in like the last half to three quarters inch it seems. Barrels are factory length. I expected a much more gradual taper.

Finally, as I got this late last night and not much time, can I expect to go from the breech end and find forcing cones in a Parker?

Any advice, thoughts...etc appreciated!