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Elkins45 · January 1, 2012, 11:19 AM

I have an Erfurt 1920 stamped Mauser action that has been sporterized and fitted with a prechambered heavy barrel in 243. How I ended up with is a long and uninteresting story.

The problem with it is that the bolt closes on a FIELD gauge. I made myself an action wrench and turned off the barrel. After a bit of research and measuring I have come to the conclusion that the chamber was originally cut too deep. I say that because the extractor contacts the breech face before the FIELD gauge bottoms out. Shouldn't a too long gauge like the FIELD protrude enough so that there actually is some excessive headspace when the parts are held together outside the action? That's my big question.

I'm thinking I need to shorten the chamber by facing off the barrel a bit. My other question is how much should a FIELD gauge (or a Go gauge) protrude from the barrel? What is the 'correct' specification for case head protrusion?

TIA for any help/advice.

January 1, 2012, 11:19 AM	#1
Elkins45 Senior Member Join Date: February 24, 2010 Posts: 498	Mauser headspace question I have an Erfurt 1920 stamped Mauser action that has been sporterized and fitted with a prechambered heavy barrel in 243. How I ended up with is a long and uninteresting story. The problem with it is that the bolt closes on a FIELD gauge. I made myself an action wrench and turned off the barrel. After a bit of research and measuring I have come to the conclusion that the chamber was originally cut too deep. I say that because the extractor contacts the breech face before the FIELD gauge bottoms out. Shouldn't a too long gauge like the FIELD protrude enough so that there actually is some excessive headspace when the parts are held together outside the action? That's my big question. I'm thinking I need to shorten the chamber by facing off the barrel a bit. My other question is how much should a FIELD gauge (or a Go gauge) protrude from the barrel? What is the 'correct' specification for case head protrusion? TIA for any help/advice.