The Technical Rifleman by Wayne van Zwoll

Author:Wayne van Zwoll [van Zwoll, Wayne]
Language: eng
Format: epub
ISBN: 9781440236563
Publisher: F+W Media
Published: 2013-01-06T22:00:00+00:00

Chapter 12

How Handloading Affects Headspace

Britain’s ageless Short Magazine Lee Enfield was given a replaceable bolt head, to adjust headspacing.

Headspace, measured from the bolt face to the cartridge stop in the chamber, is set during barrel chambering and installation.

The barrel nut on Savage 110 rifles is a clever way to make headspacing easier and cheaper. British SMLE rifles have replaceable bolt heads that varied slightly in length, for a quick field fix of improper headspace.

But as a handloader, you control effective headspace, because in sizing cases, you determine the relationship of cartridge to chamber. Even when the barrel is properly reamed and expertly installed, errors in case preparation and loading can introduce headspace problems.

Once I was sizing cases for a wildcat 6mm cartridge, the .240 Hawk. I set the die to full-length size, to ensure the cartridges would easily fit the chamber. My first shot blew gas from all crevices of the stout Remington 700 action.

The case showed a circumferential crack forward of the belt. Because the loads were not stiff, and because the bolt lift did not indicate high pressure, I fired another round. Same result. I compared sized cases with the fired cases. The sized .240 hulls were shorter by nearly .1 inch.

So I unscrewed the sizing die until it hung 1/8 inch shy of contacting the shell-holder. The first case sized at that setting wouldn’t chamber. Lowering the die incrementally and trying the case at each setting, I finally closed the bolt.

Excess headspace causes hulls to stretch unduly ahead of the web. A split, and spilled gas, can result.

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