Gentlemen,

I have come across an old mauser and I am having trouble identifing the caliber. The only markings is a 7.6 S on the top of the barrel at the breech, an I.S. 1906 on the left side of the chamber and the serial # is 86612. The guy in charge of it said he "reckoned" it was a 30-06 because a 30-06 shell would fit in it. He scared me to death. The rifle is in really good shape with a 1/2 octagonal with iron sights and the rifle has double set triggers. Anyone have any idea as to what caliber it is or where I might go to look it up?

Thanks,
David Brown

I highly recommend having a chamber cast done. That way there is no guessing.

With ealy Mausers it could be a range of calibres, a fair few that would allow a 30.06 to chamber.

Agree with the above poster, do a chamber cast.

Looking up the chamber can give you an idea of what the cartridge case looks like (ie sharp or narrow shoulder angle etc).

But also, might be worth slugging the bore with a soft lead slug and seeing what it is (ie 8mm) as this will then allow you to narrow down the cartridges.

You can start by seeing how a 30 cal bullet fits in the end of the muzzle to see if it is 30 cal or something bigger (or smaller).
Suggest have a look at COTW (Cartridges of the World) as well as it shows all likely one's in the one book.

Suggest look at the 8mm cartridges.

Also the 7.65×53mm Argentine and others.


Does the gun look like it is set up for a Rimmed or a Rebated case ?
.

7,6s is metric for 30/o6 but like DH said chamber cast would clear it up.

you might first try 06 go-nogo gages. Are you sure that S isn't a 2 ? roger

Roger go/no-go guages are only good for establishing proper headspace on known cartridge chambers , a chamber cast is the only way to know for sure. 7.6 s would make sense for the 30-06 springfield but guessing is not the way to go...

quote:

Originally posted by hivelosity:
7,6s is metric for 30/o6 but like DH said chamber cast would clear it up.

7.62m is certianly the metric equivalent of a 30 cal, but by no means does this imply the rifle is chamber for 30/06.

We would need to see photo's at a minimum.

quote:

Originally posted by fgulla:
Roger go/no-go guages are only good for establishing proper headspace on known cartridge chambers , a chamber cast is the only way to know for sure. 7.6 s would make sense for the 30-06 springfield but guessing is not the way to go...

The chamber cast may be a good way to go but it ain't the only way to skin this cat. The gages are a good STARTING point and after that you use a little brain power. Find the groove and bore diameters, base diameter, expand and size case gradually to fit and fire form with a reasonable load.
roger

Germans typically marked 1906 on 30-06 rifles and in conjunction with the 7.6 it is likely a 30-06. That said, making a chamber cast is a definitive way to know exactly what you have. I wonder if the IS is to signify spitzer bullets?

Roger is right, you know.

A chamber cast will work, but so will a .30-06 go gauge, a .30-06 field gauge, and slugging the bore.

What I'd do if I didn't have some Cerrosafe on hand to make a cast is slug the bore first, to determine an appropriate bullet diameter.

Than I'd take off the extractor and try the '06 "Go" gauge. The bolt should close easily on it.

If it did, then I'd try the '06 "field" gauge. The bolt should NOT close on it at all. (You can often force a bolt closed on a field gauge, but you'll probably futz-up the chamber, the gauge, or both , if you make the bolt close on a field gauge.) The bolt handle should just barely start to close, then meet resistance and stop. DO NOT continue closing the bolt on a field gauge past the first, slightest, feel of resistance. And DO NOT test with gauges before removing the extractor from the bolt.

Anyway, if the bore is for a .308" diameter bullet, and the bolt closes on the go gauge, and doesn't close on the field gauge, you've almost certainly got a .30-06 in your hands.

At that point I'd be willing to risk loading a cast bullet only .30-06 load in a previously unfired '06 case with about 17 grains of SR 4759 and any cast bullet of 150 to 180 grains weight. I'd then fire a round so I could look at the brass after firing and make sure.

Whatever it is, it sounds interesting.

I recognize AC as having being superior to me in most things we discuss here.
He is also more wisely prudent as regard to safe practice.
Having said that When we reach the fire forming I would use a heavy for cal. bullet driven by a modest load of 4831 or 3100. We know from the info we've collected that we have satisfied 30-06 capacity but there is still the outside chance that we are working with an IMP chamber. Blow it out and see what you got.
Remember ,working in the world of knowledgeable process, in this instance the case is the fuse in the circuit ,not the rifle.I guess what I'm trying to say is that you might have more latitude than you might think. roger

quote:

Originally posted by lee440:
Germans typically marked 1906 on 30-06 rifles and in conjunction with the 7.6 it is likely a 30-06. That said, making a chamber cast is a definitive way to know exactly what you have. I wonder if the IS is to signify spitzer bullets?

Exactly!

M

Well, let's see how many things it could be, and what might be determined in the absence of a chamber cast.

1. The head size is pretty easy to determine. Either it's a nominal .473" head of the .30-06 (7x57) family, or it's not. That's pretty easy to determine by measuring the bolt face (or seeing if anything larger than an '06 head will fit in it.

2. How long is the chamber? Outside of the Howell series of proprietary cartridges (which had their origin much later than the manufacture of this particular gun), I know of no cartridges on the .473" head which are longer than the .30-06 and its descendants (if it's a Rocky Gibbs chamber, then here, have a cigar!). If a .30-06 goes into the chamber, then the chamber is assuredly NOT for either a smaller caliber or a shorter case.

3. Assuming affirmatives to the two above, then the chamber must be for either a .30-06 or a larger caliber based on the '06 case, i.e. .333/06, .35 Whelen, 8mm/06, etc. The age of the rifle makes anything other than .30-06 doubtful (assuming it has not be re-chambered in recent years, which its markings would counter-indicate.)

4. An approximate measurement of the bore doesn't require the precision of slugging to determine what the caliber is. Just turn the inside prongs of a set of Harbor Freight and Tool $9.95 calibers upside down in the muzzle and you'll get a reading which will tell you if the bore is about .30", .32", .35", etc.

5. By the time you've done these things, you will have eliminated all but one cartridge. If you want to be doubly cautious, instead of placing a live round for that caliber into the chamber and firing it to prove that your deduction is correct, instead make a fireforming load of fast-buring pistol powder and cream of wheat filler (recipes available on numerous threads here on AR). Go out in the yard where the mess won't bother anyone and shoot it to fireform the case to the chamber. Vwallah: You have a chamber cast! And you've proven your chambering without firing a potentially dangerous load in it.

Stonecreek, point 5 is a very good idea.

Which is why I suggested a cast bullet load using only 17 grains of SR 4759. That won't be a dangerous load in any .30 bore the cartridge case is likely to fire in. Lead bullets easily conform up or down to bore or throat sizes, and in cases the size of an '06 case that is a pipsqueak load....about 1,600 fps from my '06, but IS enough to fully fire-form a case.

OK fellas, I'm sure a modest load of 4831 would be like a hand grenade !!! Choke, Choke. Right. roger

Roger -

I think a modest load of 4831 would likely be quite safe. But with my luck these days, It might BE a rifle that had some inherent weakness and sure as heck would blow up on the trial round.

Then sure as heck someone or their heir would want to sue me, claiming the cause was my specific load suggestion. So, though it might be perfectly safe to skip everything and just try a factory '06 round in it, I'd RECOMEND trying some kind of weak-kneed load AFTER taking some primary measurements, with or without gauges.

Best wishes, Sir

I was about to suggest this but Stone creek already has. I tend to just plug the case neck into a bar of soap.

Oh...if you still don't like the rifle, just give me the contact and I'll take it off your hands! It will match my Simson 9.3X62 with the octagon to dound barrel!

quote:

By the time you've done these things, you will have eliminated all but one cartridge. If you want to be doubly cautious, instead of placing a live round for that caliber into the chamber and firing it to prove that your deduction is correct, instead make a fireforming load of fast-buring pistol powder and cream of wheat filler (recipes available on numerous threads here on AR). Go out in the yard where the mess won't bother anyone and shoot it to fireform the case to the chamber. Vwallah: You have a chamber cast! And you've proven your chambering without firing a potentially dangerous load in it.

It's not marked IS, it is marked US. It is a Mauser model 1906, which were chamberd for the .30-06 cartridge. Here is pic of one just a couple of hundred off from yours (stolen from the net)

Thanks you all for the responses. I do not know what I would do with out the wealth of knowlege on Accurate Reloading forums. I know where to start.

Thanks,
David Brown