Everything You Ever Wanted to Know About ...

...checking M1 Garand headspace is covered in the CMP online magazine, The First Shot.

Written by John McLean, CMP Armorer

Everything you ever wanted to know about checking M1 Garand head space

Why should I care about the headspace of my rifle?

When a rifle is fired, the pressure generated inside the chamber rises to tens of thousands of pounds per inch. This pressure generated by the primer and burning powder can do serious harm to you or others around you if something goes wrong and the hot, high pressure gasses escape through a breech in the brass cartridge case.

Excessive headspace will cause the brass to stretch more than it should and increases the likelihood of a case failure.

Insufficient headspace may contribute to slam fires, light strikes on primers, misfires and more wear on parts due to the additional force needed to chamber the rounds...

This is an excellent article on headspace. Head on over and give it a read.