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headspace gauge

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Unread 01-26-2003, 04:03 PM
Junior Member
Join Date: Aug 2002
Location: texas
Posts: 18
headspace gauge

i'm looking to get an headspace gauge for sevaral of my guns. i really never paid attention to the headspace measurments before. is the headspace gauge is a tool to tell you if you are oversizing your cases when you compare them to an actual case that has been fired in that particular gun? and what brand to get? i realy like the stoney point tools since i have the bullet comparator.
thanks guys

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Unread 01-26-2003, 04:34 PM
Gold Member
Join Date: Jan 2002
Location: Wenatchee, WA
Posts: 806
Re: headspace gauge

The headspace measurement in most(all) of the cartridges I use is from the bolt face (base of the case) to a datum line, usually at the midpoint of the shoulder angle on rimless cartridges. On magnums, unless you have had the chamber custom cut so that it headspaces like a rimless case, it headspaces on the belt, which is really hard to control w/ normal dies.

Most of the factory dies I've had say to screw them in to where they just contact the shell holder w/ the ram at the top of its stroke. That should make the case chamber in just about any gun in that caliber out there. In reality, I don't care about my cases chambering in any gun but mine, so that is un -neccessary overworking of the brass.

As an example of which I happen to have the numbers in my head, I recently screwed a takeoff .243 Win barrel on my Rem 700VS. The .308 Win family of cartridges (.243 Win, .260 Rem, 7mm-08 Win, .308 Win) headspace on the datum line, which measures 1.630" from the bolt face. Fire formed a couple cases w/ light loads, and came up w/ a fired headspace dimension of about 1.635". Screwing in the dies all the way per the directions sized the cases down to 1.619". Waaaaay oversized. Adjusting the die to where I had just a smidge over 'nominal' spec headspace, or about 1.632" still allows the case to chamber fine in my gun, but w/ minimal working of the brass.

You can either use the RCBS Precision Mic tool, which you have to get one for each cartridge you load for (in reality, I never use the bullet seating half of the tool, as I have a Stoney Point OAL Comparator, so I could use the headspace portion for cartridges w/ similar headspace dimmensions like the .243 and the .308). It doesn't give you a number like 1.630", rather you see it as being over or under spec as viewed on a micrometer scale.

I eventually opted to get the set of headspace comparators from Stoney Point, where you look up which cartridges use which insert (based on shoulder angle, I think), mount the insert, zero the calipers (I'm using a set of digital Mitutuoyos), and check the head space.

Lastly, there is the Redding dial indicator die, can't remember the name. Haven't used it, and probably won't w/ the Stoney Point inserts. They are accurate enough for my uses, and at this point, there's no sense in spending $30-40 per cartridge for a Precision Mic or Redding dial indicator.


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Unread 01-26-2003, 08:20 PM
Junior Member
Join Date: Aug 2002
Location: texas
Posts: 18
Re: headspace gauge

thanks milanuk for your reply. my next question is if i started neck sizing the cases after the first full sizing, do i still need to worry about the headspace measurment? i have never neck sized, i'm still trying to get my equipments in order.

[ 01-26-2003: Message edited by: sambo ]
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Unread 02-02-2003, 08:43 PM
Silver Member
Join Date: Dec 2002
Posts: 374
Re: headspace gauge


No you don't need to worry about the headspace when neck sizing. You really don't need to worry about it when FL sizing. FL size your cases so they fit with (just barely) NO effort on the bolt. After firing them if you want to neck size, only go down the neck 60-70% of the neck length and you will leave a small bulge at the neck to shoulder junction that will center your bullet perfectly in the throat and will also help to seal your case/chamber when fired. When you start to need effort to close the bolt on a round, FL resize again just as before. If it only takes 3 or less firings till you need to FL size, then perhaps that gun is being shot too hot or in the case of a large magnum, you have a gun that simply needs the cases resized more often in order to function properly and be safe.

There may be exceptions out there, but I would say that most guys out there who neck size, are shooting a smaller case and those who shoot, say, guns from a 7mm Mag and up, almost allways have to FL size. There's just too much strech in the gun when it's fired.
If you have something that you disassemble and reassemble enough times, sooner or later, you'll have two!
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