It is actually very easy to check. Get a caliber specific "GO Gauge" and put it in the chamber. The bolt should close smoothly like there is no shell in there. You can then install a NO Go Gauge and make sure the bolt will not close all the way. You can also use the GO with a piece of tape on the "primer" end to do the same thing. While you are at it, check to make sure the ejector parts on the head are not damaged or sticking.