I hope this is the right place to post this (if not, move or delete as needed.) In addition to the other sources of headspace gauges, a fellow on one of the other forums is making gauges. (he just got all the equipment set up.) Google Okie headspace gauges and you will find him. I have no business ties with this fellow, just bought the gauge. (no go.) Very good quality and a good finish. I thought others might be interested in another source of gauges.
Ps... He also makes gauges for .303 Enfields
If at first you don't succeed, chamber another round and fire again.