Wow, okay so based on those tolerances length can currently vary by a .100" and diameter by .010" at the extremes. When gauging a chamber, especially with an double ogive like Parkers had or a shallow forcing cone it seems it would be easy to get a false long reading to the start of the forcing cone. I've carefully remeasured a couple chambers and in one case a chamber I thought was 3" was actually 2 7/8". My Winchester 21 stubbornly continues to measure at 2 5/8" and I seem to be feeling a definite stop. Yet the chamber could be undersized by modern standards at the end of the chamber. I'll see what it gauges with a .793" min. gauge.
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