If you have older rifles, especially military rifles, a set of headspace gages are needed to help ensure safe firing. Even older military cartridges link 7mm Mauser, 30-40 Krag, and 7.62x54R generate lots of pressure. Headspace is important in all these cartridge and rifle combinations. An accurate way to measure headspace is with a good quality gage.
Some excellent headspace gages are made by Okie Headspace Gages. As their name implies, the company is located in northern Oklahoma. They manufacture GO, NO-GO, and FIELD gages. The FIELD gages are used in older military rifles that may have generous chambers. They have excellent instruction on their website and it’s very easy to order what you need online. Visit them at www.okiegauges.com