Maybe both tools are errant?
Buy the no-go and be done with it.
You don't need measuring tools at all other than the chamber gauges.
Here's one to ponder on I have a PTG go gauge that is laser etched 257 roberts ackley improved 40°. It is .018 shorter than it is supposed to be. Or the dies I've used for 15 years are .018 deep. After reaming to match the dies fired brass measures to print so the go-gauge was obviously marked wrong and is meant for something else.
Trust but verify!
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