I have 2 methods for checking headspace and I only use them on Mosins if I suspect there may be a problem. Method 1 is to put 2 layers of regular masking tape on the bottom of a spent case, cut to fit the whole circular base of the case. If the case will chamber, it may have excessive headspace and should be checked by a smith. Method 2 is easier. Tie rifle to something (a tire works), point downrange, chamber a round and with a long string pull the trigger from a good distance. Check the case for bulges/problems near the rim. BTW, method 2 may create a bit of a fright at a populated range.
