Crimp questions

When people refer to measuring crimp they're talking about the diameter after the round has been loaded and at the upper most part of the case mouth... is that right?  And from what I gather, it is difficult to measure with common measuring tools most of us have on hand like calipers?  Seems to be for me.

Seems like there are common crimp diameters most go for.  What are the ranges for crimps for 45 and 38 most commonly used?

Sorry to be pedantic, but these questions would best go in the Ammunition section.

Your subject comes up very frequently, a search or even browse that section will get you your answers.

How I do it.the knuckle is the resting place for the caliper.

Generally, it’s the amount of crimp your biggest buddy can’t push the bullet back in the case while pressing it against a solid object. Floor, table etc.