The Forster 303 British Headspace Gauge might save you a lot of time and trouble before you buy a Lee Enfield or if you have one already but are not obtaining satisfactory results. The topic of 303 Headspace is a minefield as there are so many ‘experts’ out there. Consult a reputable trustworthy gunsmith if you are in any doubt as this is a safety issue.
Headspace in 303 British Cartridge rifles is measured at the rim an not at the shoulder as with rimless cartridges. Unfortunately, Lee Enfield actions can stretch with use due to their design. Headspace can often be corrected by having a gunsmith swap the bolt head with another. Excessive headspace is one of the factors that causes premature case failure in the 303 Cartridge. Often, wartime chambers were made longer than current SAAMI specifications to allow room for foreign debris. This excess chamber length combined with excessive headspace can be dangerous as well as cause premature case failure as there simply too much room for the brass to expand properly.
Your bolt should not close on a the Forster 303 Headspace Field Length Gauge. New barrels are fitted using Go/No Go gauges. Field gauges are ‘longer’ than No Go Gauges.
David Watkin (verified owner) –
Item in stock, fair price and delivered promptly – thanks!