Mexican Mauser pictures and questions

I have this 1934 Mexican Mauser that is a family heirloom of sorts that I inherited from my father. It was given to my father when he was 18 by his uncle. His uncle was a gunsmith of sorts and he sporterized the rifle and made the stock. When my father got the rifle he rebarreled it to .257 Roberts Improved. When I received the rifle the stock was not finished and the safety did not work. I stained and finished the stock, found that the safety had never been fit so I fit it, and got the bits of surface rust off of it.

Here she is;

Attachment 27005

Attachment 27006

I do have a couple questions about it. First, what model/kind of Mauser is this considered?

Second, does anyone know any history of the Mexican Mausers? They dont seem very popular.

Last, and I guess it is more of a gunsmithing question but, where can I find a set of go/no go chamber gauges for .257 Roberts Improved? I can find .257 Roberts and .257 Roberts Ackley Improved, but not not the Roberts Improved. I am concerned because I know that my father installed the barrel and I dont think he gauged it, especially after seeing the lack of fitting of the safety. The rest of the work looks very solid but I would rather be safe than blown up.

Thanks in advance for any info you can provide. :)

Hello, it might be the model 1910 Mauser.This was the first Mauser produced in Mexico. The 1910 model is based on the model 1902. The model 1910 was phased out in 1934.Cal was 7x57 hopes this helps

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Originally Posted by topaz

Hello, it might be the model 1910 Mauser.This was the first Mauser produced in Mexico. The 1910 model is based on the model 1902. The model 1910 was phased out in 1934.Cal was 7x57 hopes this helps

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Thanks. Do you know what the predecessor was? Since this one has 1934 on it I guess it could go either way if the 1910 was followed by another Mauser.

It's likely Ackley Improved but just doesn't state it. But it really doesn't matter, since you have to fire form the cases anyway. Just don't fire regular factory Roberts ammo through it if you are worried about case head separations. If you are REALLY curious, you could do a chamber cast, but I think its simpler just to do one round up using standard case forming procedures and measure it after you fire. Then you can send the fired case off to have custom dies made if it's not one of the "regular" wildcats.

Just don't lower the fireform charge too much, or the primer setback (actually it is case "blowforward" by the primer ignition pressure) won't be overcome and you WILL think you have excessive headspace when it's really not there.

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Originally Posted by subijitsu

Do you know what the predecessor was?

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Self correction. I meant successor not predecessor.

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Originally Posted by jmoore

It's likely Ackley Improved but just doesn't state it. But it really doesn't matter, since you have to fire form the cases anyway. Just don't fire regular factory Roberts ammo through it if you are worried about case head separations. If you are REALLY curious, you could do a chamber cast, but I think its simpler just to do one round up using standard case forming procedures and measure it after you fire. Then you can send the fired case off to have custom dies made if it's not one of the "regular" wildcats.

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I hope it turns out to be Ackley Improved. The barrel doesnt say Ackley but I am guessing it is from the 70s so who knows. I do know the .257 Improved has a 28 degree shoulder angle while the Ackley Improved has a 40 degree shoulder. It should be fairly easy to see once I get a case fireformed. Of course the datum on all three is different.

It was suggested to me to load up some .257 Roberts casings and load the bullets to the lands. This will ensure that the casing is held against the bolt face in case of excessive headspace while fireforming. I can neck size from then on and not worry about headspace. I dont know if I want to go this route but I may use it to figure out the chamber then pick up some of the correct (and costly) FL dies.

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Originally Posted by jmoore

Just don't lower the fireform charge too much, or the primer setback (actually it is case "blowforward" by the primer ignition pressure) won't be overcome and you WILL think you have excessive headspace when it's really not there.

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Ah, I didnt think of that. Makes sense. I probably would have started with a light load and worked up. Now I will start with a lower middle of the road load (if that makes sense :confused: ) so I can get a complete fireforming.

P. O. Ackley wrote a book that covers pretty much all you need to know about fireforming and working with wildcats. Only the powder selection has improved. Can't think of the exact title right now, but it's probably pretty obvious.

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Originally Posted by jmoore

P. O. Ackley wrote a book that covers pretty much all you need to know about fireforming and working with wildcats. Only the powder selection has improved. Can't think of the exact title right now, but it's probably pretty obvious.

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Ackley was definitely a genius. I would love to read his book, although it would probably go over my head. I have an article saved somewhere that he wrote about headspacing, Ill see if I can dig it up.