Headspace Checking

[raindog]

I have a Turk Mauser (1891-style Mauser). I've had it for years and never shot it. It's a typical Turk, rechambered at Ankara in 1930 for 8x57.

I took it to a gunsmith a few years ago and he said there was excessive headspace according to his gauge. He has a good reputation but his main business is hunting rifles and modern gunsmithing. He advised me to grind down the firing pin and hang it on the wall.

I read that most gunsmiths safety check with NOGO, not FIELD gauges. After reading up, I decided to try a FIELD gauge. I bought a Forster 8x57 and the bolt does not close with this gauge loaded. The bolt won't go past about 60% or 70% closed...no amount of (reasonable) force will close it - I didn't jump up and down on it or anything.

So I'm wondering what conclusion I should draw is. Is this safe to fire? Should I take my FIELD gauge and go have a talk with the gunsmith (or a different one)?

I'd rather not catch an 8mm bolt in my eye due to some horrible explosion, but this is the only rifle I've ever owned and not fired :-)

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[rangerbluedog]

I think I'd find another gunsmith - one with a reputation for having knowledge concerning old milsurps.

[kwg020]

Buy a NO GO gauge and check it. I have an old 93 I shoot occasionally with hand loaded ammo that will almost close on a field gauge. The brass stretches a little but it reforms nicely. I wonder if he thought it was too tight and would not close on a GO? Since he apparently never said one way or another. I think I would spend the money for a NO Go gauge and you will know the answer for sure. Get one the same brand as what you have. kwg

[raindog]

Update - go a NOGO gauge (Forster). It does close on a NOGO.

So: it does close on a NOGO, does not close on a FIELD, though the bolt comes around about 60-70% of the way.

To set the barrel back and correct the headspace is probably $225...I paid $25 for this rifle in 1988 or so and have never shot it LOL.

[rangerbluedog]

I'd fire that rifle.

[NRA]

IMO this head space issue is way over rated. Just check your fired brass for any defects. I fear I will get a tongue lashing for this though.

[Patrick Chadwick]

The standard joke answer is "Don't fire it - give it to me!"
The serious answer is that either you use gauges seriously or you don't use them at all.
According to the gauges you have used, the rifle is acceptable for use. Out of tolerance for a new rifle, but not unusable. So if you take gauges seriously, what are you worried about?

I do not use headspace gauges. Because...

1) The fact that a rifle passes a headspace gauge test DOES NOT PROVE THAT IT IS SAFE TO FIRE.
Apologies for shouting, but there was a case recently of a Lee-Enfield (see the forum) that appeared to be OK but had been drilled through the chamber to fit a pin to render the chamber unusable. The pin was missing and the result was a highly dangerous rifle. No headspace gauge could reveal that. Nether can a gauge show up a cracked receiver. Or a blocked bore etc etc etc.

In fact, there is no ultimate, 100.0000% proof that a rifle is safe to fire. A proper proof firing conducted by a proof house is the best one can do. All you or a gunsmith can do is check that there is no evidence that it is unsafe.

2) The fact that a rifle fails a headspace gauge test DOES NOT PROVE THAT IT IS UNSAFE TO FIRE.
I have fired rifles with a headspace so huge that ignition was only possible because the extractor was holding back the cartridge case sufficiently for the striker to ignite the primer. The cases were stretched, but nothing else happened.

3) Do not base your judgement solely on a headspace gauge test.
A rifle that fails the field gauge test should certainly be inspected very closely. Look at the bolt lugs, for instance. Severely set back or worn bolt lugs would indeed be a potential hazard. But such checks must be performed regardless of the results of any gauge test.

4) Military rifles were often made to a more generous tolerance than new, modern designs made to CIP/SAAMI standards, so tests with commercial headspace gauges are frequently pointless as a safety indicator.
CIP and SAAMI are manufacturing tolerance standards, not safety standards. Non-adherence to these standards warrants further investigation, but conformance is not a guarantee of safety. If you search the forums you will find mention of the Swedish Mauser and a link to a site showing the real Swedish military headspace gauges. All Swedish Mausers are out of spec according to SAAMI. But not dangerous because of that. They were in fact mostly built before SAAMI was invented. As were many of those old service rifles we treasure - and shoot!

I repeat, I do not use headspace gauges. I check the head clearance (described several times in the forums) - a practical test. Now you know why.

[WCBeck]

If you are worried about holding it to shoot it tie it to an old tire and put a string on the trigger. Then you can inspect the fired case.
wcbeck

[PaulN]

raindog has brought up an interesting topic (especially for us owners of ancient military rifles).

Let me throw out a comment and see if there is any disagreement :

For a bolt action rifle the most desirable amount of headspace is where the bolt will just close (without undue pressure) - this should result in maximum support to the rear of the brass.


To me the most perplexing part of trying to understand headspacing was that descriptions were not at all clear on what was meant. As I thought about it to a greater degree, and read more, it became clear that at least part of the problem is that the 'official' definition of headspace is measured from the point in the breech that prevents the cartridge from going any further back to where the head of the brass cartridge case is. For a rimmed cartridge like the British .303 this is easy to understand as it is what your intuition tells you. For any other type of cartridge you have to ask yourself 'What keeps this cartridge from going further ?' For rimless cartridges with the 'classic' Mauser .473 inch diameter cartridge head this means looking at where the brass case is swaged down to the diameter necessary to provide a snug fit around the bullet. I believe (?) that for these cartridges the 'stopping point' is defined as half-way along the swaged area; with that as the 'zero point' the distance back to the rearmost part of the cartridge case is the measured headspace (even though what we're really interested in is how much space exists between the cartridge case and the bolt head).


Any disagreements ?

[Calif-Steve]

You have good advise here. It is likely quite safe. I have tested a number of early Gew98's and they tend to run generous headspace. If a field gage is fine, I would stop worrying. Also, I would use American 8mm ammunition as, the European 8mm is very stout. Handload down and be careful.