headspace gauge

[sambo]

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

sambo

 

[milanuk]

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.

HTH,

Monte

 

[sambo]

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.
sambo

[ 01-26-2003: Message edited by: sambo ]

 

[4mesh063]

sambo,

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.

 

[TrickyDick]

Howdy,

I am a new reloader. Been reading a lot, but only recently been able to acquire components to reload. I began with a bucket of brass from my friends backyard range and started sorting, decapping, cleaning, and then ultimately resizing per supplied die instructions (I didn't have case gauges or headspace gauges at that time). Then I cleaned the lube off and trimmed the cases to the trim to length in my manual, and had them waiting to load.

So I realized I needed a case gauge and checked the sized cases and seemed to be good. I found primers and primed about 50 Win 308 cases and was preparing to load. Then I realized, geez, I need to check the headspace.

Here is where my problem starts.

My (now primed) cases are all over the place with headspace.
I saw the SAMMI spec for " go " 1.630, and "no-go" 1.634 and "Field" 1.638
Mine are all shorter than this, but so are some other cases I measured.
My main concern is, having a "short" headspace, will this cause damage to my rifle when shooting as the case head slams against the bolt face? My understanding was that the term headspace meant the space between the case head and the bolt face as an expression of the length of the case from the datum point to the case head. and that as the chamber wears out, the point at which the datum point rests can elongate, resulting in a lot of slop or excessive space between the bolt face and the case head? doesn't the same situation apply if the case shoulder is pushed back too far? If so is there a range of acceptable tolerances for this?

Here are my measurements:

my 50 sized cases ranging between 1.626-1.619 (more than half of them are .623/.624)
Measured 2 commercially loaded cartridges 1.625/1.626
My commercially prepared modified case 1.626
A "ready to load" once fired case from "Top Brass" 1.623
A fired case unprepped 1.629

So it seems that the only thing I am certain of is that I should more carefully set my sizing die up so that it doesn't push back the shoulder too far. At some point I will make measurements in MY rifle to see how much the cartridge elongates with firing to know how far to push it back. I would however also like to load to SAMMI specs to shoot in any rifle.

Hoping someone can give me a bit of clarity with this subject, and this forum seemed to be a good place to ask.

Sorry for posting to such an OLD thread, but it seemed relevant.

After some further thought, I realize my Hornady LNL headspace measurement is called a "COMPARATOR", so although I get a measurement, it may not be precisely the exact measurement, but reflects a relative comparison between cases. In light of this, which of my cases should I reject?

If the commercial cartridges were 1.625-1.626 and my sized cases ranged from 1.626 to 1.619 I'm thinking maybe toss the shortest 1.620 & 1.619 putting my range of sizes within 0.005 of commercial cases? That would be only 4 four the 50 (actually 51) cases.

Thanks for any advice!

 

[Snyderite]

There's a rental place in Kalispell MT I used to rent my 6.5 gauges. 20 bucks and you get en for a week or two. Can't remember the name.