Mauser headspace

[Glock517]

I recently aquired a model 1938 Turkish Mauser in a trade from another member. I thought I would have the headspace checked before firing the rifle due to the issues I had read about headspace in these old Turks.

I took the gun to a local shop that charged me $26 and took 2 days to tell me that the bolt closed on the no-go guage--and my rifle is not safe to fire. I had researched enough to know that these old military rifles should be checked with a field guage as well. When I asked the gunsmith if he had used the field guage, he said he was trained that if the bolt closed on the no-go, it is not safe to fire.

I check with a few other local shops and inquired if they use the field guage to check headspace, and no one does. I also checked with a shop who does machining and found that it would cost at least $125 to correct the headspace issue.

At this point I am unsure how to proceed. I can purchase a field guage in 8mm for about $30, but I'm reluctant to sink more money into this.

I'm tempted to fire the rifle and just inspect the spent case for damage... Or, does anyone have an 8mm field guage that I could use? Or, know where I can purchase one cheap? Any other suggestions or feedback is welcome.

Thanks!

[King 5.45]

I recently aquired a model 1938 Turkish Mauser in a trade from another member. I thought I would have the headspace checked before firing the rifle due to the issues I had read about headspace in these old Turks.

I took the gun to a local shop that charged me $26 and took 2 days to tell me that the bolt closed on the no-go guage--and my rifle is not safe to fire. I had researched enough to know that these old military rifles should be checked with a field guage as well. When I asked the gunsmith if he had used the field guage, he said he was trained that if the bolt closed on the no-go, it is not safe to fire.

I check with a few other local shops and inquired if they use the field guage to check headspace, and no one does. I also checked with a shop who does machining and found that it would cost at least $125 to correct the headspace issue.

At this point I am unsure how to proceed. I can purchase a field guage in 8mm for about $30, but I'm reluctant to sink more money into this.

I'm tempted to fire the rifle and just inspect the spent case for damage... Or, does anyone have an 8mm field guage that I could use? Or, know where I can purchase one cheap? Any other suggestions or feedback is welcome.

Thanks!

You shoot the thing like that they just might find what's left of your face over yonder in Mount Union.

The minimum headspace gage is often referred to as a go gage, and verifies that the chamber being measured is at least long enough for the intended cartridge. The maximum headspace gage is often referred to as a no-go gage, and if accepted by the firearm verifies that the chamber being measured is too long for safety.

[bigedp51]

8x57 headspace gages
1.874 - GO
1.880 - NO-GO
1.884 - FIELD

Simple headspace check without headspace gages.

Take a empty unfired cartridge case or a full length resized empty cartridge case and measure its overall length with a set of vernier calipers and write it down.

Now insert a spent fired primer in the primer pocket just using your fingers to start the spent primer into the primer pocket.

Now chamber this test round slowly closing the bolt and seating the primer, now open the bolt and remover the cartridge case.

Now remeasured the case and write it down, you will see the primer protruding from the rear of the case. The amount the primer is protruding is your head clearance or the "air space" between the rear of the case and the bolt face.

Now subtract the first case measurement from the second measurement and this will give you the head clearance measurement in thousandths of an inch.

If you have more than .017 you are over the FIELD gage measurement (approximate) plus or minus .001 to .002

If you are under .017 you have "less" than a FIELD headspace gage reading.

Note, this is based on the minimum SAAMI case length for the 8x57 Mauser.

Examples below are .303 British cartridge cases.







After using the bolt to seat the primer the amount the primer protrudes is head clearance.



Headspace and head clearance examples below, remember head clearance is the "air space" between the rear of the case and the bolt face and the amount the case can stretch when fired.



And sometimes a half inch of excess headspace means nothing.

[bigedp51]

Note the Mauser rifle is a control feed action and the claw extractor holds the cartridge case against the bolt face as a safety feature. In simple terms a Mauser type action can safely fire a cartridge with excess headspace.

Below is a British .303 Enfield with a reloaded case that is ready to have a case head separation when fired. The action has been wrapped with a piece of paper to show the results of a case head separation.



Below is the cartridge case a piece of paper after the case separation, please note that the paper has not been torn or blasted apart.



There is a difference between a case head separation caused by excess headspace and a total cartridge case failure at maximum chamber pressure.

[King 5.45]

Even Mausers can kB:

[762xIan]

I check with a few other local shops and inquired if they use the field guage to check headspace, and no one does. I also checked with a shop who does machining and found that it would cost at least $125 to correct the headspace issue.

I sure don't know what a "machine shop" is going to do to "correct" it. The only way to to fix it is to replace the barrel. This should cost only about $100 plus the cost of a new barrel from any gunsmith which should be a routine job. Especially on a Mauser action which historically is probably the most popular and numerous rifle encountered by smiths for work.

As far as closing on a no-go....well there is more to the story, I had both a Garand and a Mauser that would close on a No-Go...WITH FORCE, but not close on a field gauge. The Garand lasted many hundreds more rounds before the muzzle and throat erosion affected accuracy and I had it rebarreled. The Mauser I still have and it shoots fine still.

Even Mausers can kB:

I doubt excessive headspace would cause a KB like that....that looks like a bad reload....is there a story with that picture?

Any other suggestions or feedback is welcome.

You could always use the action as a platform for a custom build, aftermarket Mauser barrels in many calibers and styles abound, as do custom stocks. Just an idea.

[bigedp51]

Glock517

I have headspace gages for my collection of Enfield rifles and .223/5.56, .308/7.62 BUT headspace gages on milsurps can be deceiving because if you shoot and reload commercial cartridge cases headspace reading can be more complicated. A military chamber is longer and fatter than a civilian commercial rifle chamber and our commercial cases were not designed for military chambers.

Case head separations on the Enfield rifle are an everyday occurrence and no one is ever injured because of the gas venting system on military rifles.

On the Enfield rifle below I have tested headspace settings from .010 over maximum to .005 under minimum and checking how much the commercial cases stretch in the base web area. (.084 to .059 and normal headspace is .064 to .074)





Below is an example of case head separations on a commercial rifle and "NO ONE" was injured during this test below.








The 5th rifle from the front is a 8mm Yugo 24/47 Mauser and I do not have headspace gages for it and all I used was the primer method to check head clearance to find out this Mauser was in good shape.



And I don't use a paper clip to see how far my cases have stretched in the web area when fired.

[Ecclectic Collector]

As an owner of a dozen 8mm mausers I invested in a set of headspace gauges that I got from Jantz tool company. You can google their webpage.

My gauges cost me about $13 each. I bought both No Go and Field gauges. As explained to me (and born out in practice shooting all of my rifles) is that the No Go will show if your rifle is slightly out of spec-but still within safe shooting condition while if the bolt closes on a Field gauge it will cause case head separation.

I have never had problems with case head stretching in my mausers, even then ones that the bolt does close on the No Go gauge. Having so many different rifles I full length resize with each reloading too so my ammo will fit in which ever gun I take out to shoot.

Frankly I think the owner of the gun shop that offered to fix your gun is full of something. You do know that you could quite possibly get a replacement bolt that fits your gun well enough to have it be fully in headspace (though as I've explained this isn't essential). Try Springfield Sporters in Penn Run Pa if this is the route you'd consider going.

Hope this helps.

[bigedp51]

Glock517

Ecclectic Collector has just given you some very good advice, what many of you are forgetting is the Mauser rifle has a claw extractor that holds the cartridge case against the bolt face making a case head separation a rare occurrence. (very hard for the case to stretch)


Below, types of excess headspace. (with a little humor)









Below is what happens when the cartridge is held in close proximity to the bolt face, even with a 1/2 inch of longer headspace. Remember your Mauser has a claw extractor holding the cartridge case!





If you look at the center fired case in the photo above, you can "see" how far the primer backed out of the primer pocket on this .308/7.62 case. The amount of primer you see protruding is how much actual head clearance the cartridge had when fired which was NOT the full 1/2 inch of free play in front of the case.

[knight0334]

If you aren't willing to rebarrel, or turn the old barrel back and rechamber - you can fireform brass to the existing chamber and "wildcat" it.

NOTE: I accept NO liability for any attempts that result in damages or injuries. By doing the following you, your estate, and lawful heirs accept the responsibilities for what may result.

Two ways to do it, first - anneal some brass:
1. using cream of wheat over a powder charge, fire the cream of wheat load. The brass will expand to the chamber. From then on out only neck size the brass. http://www.angelfire.com/ma/ZERMEL/fireform.html

2. using a fireforming load with a real bullet. You want to keep pressures low, but just high enough to form the brass to the chamber. neck size only the brass from then on out.

The gun wont technically be a 8mm Mauser anymore because the dimensions of the chamber and brass wont be to spec. It'll be a sort of wildcat. Once you've formed some brass to the new chamber dimensions and fired them with proper loads after the reforming - you can then send a fired case to RCBS or another die maker and have them make you a set of full length dies to match the new chamber/cartridge. Keep in mind that the present chamber is longer/larger than the spec brass. You will thin it out some when it expands to the new chamber. Your new loads will have to keep that in mind.

I personally recommend rebarrelling or having the existing barrel turned back one thread then rechambered.