start by sliding a piece into the barrel and look at how it fits. Easy to do as the barrel is off and in your hands. Make sure it bottoms out with a very lite tap. if it goes to deep and you do not have the full extractor groove showing, or appears to have to much case sticking out, you will have to start measuring your brass to see if it is the right size and / or You should have a smith check it to see that the chamber was done properly. I have bought a couple barrels that were RE chambered and not quite right.
One was to deep. barrel would screw tight to the bolt head. Case went in to deep and It would only extract after firing. the case was blown back into the bolt head. one cure would have been to raise the die and not push the new shoulder back down creating a larger volume case, BUT I would have had to fire all the cases to make them this way and that might not have turned out well!
If the cases stick out to far, you get into thinner metal and the cases could or will separate int 2 pieces. This can also happen in a proper chamber if you reuse (reload) a case to many times. each firing makes the case thinner.


I forget the exact measurement for case protrusion and am not where I can look it up so I will leave that foe some one that has the information to post rather then guess wrong.

If your case fits properly you are good to use it for a gauge.