Quote:
As a Brit, can I please repeat that US ".303 Brit" headspace gauges are in fact Krag gauges, and are thus Too Short. And wrong.
The British military changed the acceptable max head space early on. Commercial sporting rifle Headspace for the .303 was .068, military max specs were at first .072 later changed to .074.
Quote:
Regarding barrel proof, refer to page 12:
(g) Proof. - The barrel will be submitted with the action attached for proof. The distance from end of bolt to face of barrel will be tested with a cartridge head gauge .067-inch. The proof will then be carried out with a proof cartridge, the charge being about 33 grains of No.3 cordite, having a service bullet of 215 grains, giving a mean pressure not below 24 tons per square inch, after which the action will be examined; and the barrel, body, and bolt head will be marked with the proof mark."
I have two sets of commercial Chamber drawings, both state that maximum headspace should be no more than .071.