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wncchester · April 5, 2012, 07:50 PM

Forget "headspace", it's a measure of the chamber - only - and is virtually irrelivant to a competent reloader. Thus, how it's measured and set by the manufactor is meaningless to us.. we live with what ever chamber we have.

Ignore all the technical explainations and think of headspace as the firearm's space for the cartridge; if the space is too small we can't chamber a round, if it's too large the cases will have to expand too much each time it's fired and that leads to excessive case stretching and will - eventually - result in a head seperation, which ain't good!

Reloaders only need to know where the shoulders of the fired bottle neck cartridges are and adjust their FL dies to restore that measurement during sizing. It matters not if the case is rimmed, rimless or belted, we just resize so the shoulder is at the same place or a tad less than the fired location and that's perfection. (It's NOT necessary to set the shoulders back an additional few thou, the fired cases have already shrunk back a thou or so from the chamber size.)

You can adjust cases to custom fit a chamber by carefully running the sizer down while doing test fits in the rig but it's harder to do correctly than it may appear. Most of us use a case shoulder gage such as the Hornady, Sinclair or RCBS Precision Case Mic. All reloaders need a 6" caliper anyway so getting one of the moderately priced Hornady "headspace" kits to use on a caliper is the most flexible and cost effective way to go and you can set your sizers very precisely with that combonation.

There is no way to 'adjust' anything but the case length itself in straight walled cases but few of them ever grow too long anyway. If they do get too long we use a case trimmer to fix 'em.

April 5, 2012, 07:50 PM	#28
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	Forget "headspace", it's a measure of the chamber - only - and is virtually irrelivant to a competent reloader. Thus, how it's measured and set by the manufactor is meaningless to us.. we live with what ever chamber we have. Ignore all the technical explainations and think of headspace as the firearm's space for the cartridge; if the space is too small we can't chamber a round, if it's too large the cases will have to expand too much each time it's fired and that leads to excessive case stretching and will - eventually - result in a head seperation, which ain't good! Reloaders only need to know where the shoulders of the fired bottle neck cartridges are and adjust their FL dies to restore that measurement during sizing. It matters not if the case is rimmed, rimless or belted, we just resize so the shoulder is at the same place or a tad less than the fired location and that's perfection. (It's NOT necessary to set the shoulders back an additional few thou, the fired cases have already shrunk back a thou or so from the chamber size.) You can adjust cases to custom fit a chamber by carefully running the sizer down while doing test fits in the rig but it's harder to do correctly than it may appear. Most of us use a case shoulder gage such as the Hornady, Sinclair or RCBS Precision Case Mic. All reloaders need a 6" caliper anyway so getting one of the moderately priced Hornady "headspace" kits to use on a caliper is the most flexible and cost effective way to go and you can set your sizers very precisely with that combonation. There is no way to 'adjust' anything but the case length itself in straight walled cases but few of them ever grow too long anyway. If they do get too long we use a case trimmer to fix 'em.