Gents,
What have I got? I bought a rifle off an old timer some years ago. I bought it as a parts rifle, as it has a very nice Mexican Mauser action. He told me it was a 7x57. It looks like a late 50's custom, and all the metal work is top shelf. It has a stepped barrel on it with a series of Belgium proofs. The caliber stamped on it is 7m/m Mr. It also has the word
B. Blindee stamped on it, which I know means "for jacketed bullets" It sat in the safe for years before I ever dug it out.

The short story is I finally took the rifle out and shot it. The cases that come out don't look like the cases that go in...
I have good photos to show, I just don't know how to post them.
If one of you can help me with how to post photos, I'm sure this will be an easy one for you guys.

The fired cases extract easily, are very nearly the same length (maybe .020" shorter)as standard 7x57 cases. The shoulder is pushed slightly forward, and the shoulder angle is sharper. What really throws me is the shoulder has what looks like a radius (ala Weatherby) rather than a defined angle.

Thanks for your help,
Michael

This is just a guess, but I'd bet the brass needs more fire forming. You need to neck size the cases, seat the bullets further out and fire them again. The best way to tell what you have got is to cerrosafe the chamber and send the casting off to a die maker. He'll reproduce the cast into a set of dies for you, tell you what the ctg and stamp the dies with the information.

If the headspace is not quite correct often the case will have radiused shoulders when they form. Hill Country Rifles built a .280AI that was chambered to deep and had the same problem. If the headspace is correct you should not have to seat the bullets into the rifling as the case will be held very tightly at the neck/shoulder junction.The bolt will close very tightly on standard round before forming and will engrave a light ring at the base of the neck.There are ways to make the case headspace properly before fireforming if the chamber is a little long.

The safest bet though is to have a chamber cast made like 3sixbits recommended and be sure of what you have.

Compare your case to the following dimensions.

It sounds to me like you have a 7x57 Ackley Improved and the load you were shooting was not fully fire forming the case. You are a lucky rascal if you have the Ackey Improved version of the 7x57, but it means that you will have to reload.

Ok,

I checked the fired cases that I have against the kindly supplied 7x57AI dimensions. It's close but no cigar... Perhaps the cases are in fact are not fully formed.

While I've reloaded for 25 years, I've never had to fire form cases for any of my rifles. How much horse power does it take to fire form cases? The loads I shot in this rifle were loaded for my Ruger M77, and are pretty "soft".

Thanks to all of you for input. Now can anyone tell me how to post photos???

Michael

If it is a Mexican Mauser it must be a 93, so you should load for a 93 Mauser! It can't take the pressure a 98 will but it will do fine with factory loaded ballistics! It should fire form nicely! I have fire formed with just putting Kapock over powder and formed perfectly! I shoot two Ackley cartridges, 338/06 AI and the 257 Roberts AI. A properly chambered Ackley chamber will use factory rounds before they are fire formed. After that you need only neck size and each rifle usually only shoots its own case after they have been fire formed. They are custom chambers and each one maybe a little different. If one rifle builder builds a few rifles he can keep the chambers close by using the same case lenth gauges in each rifle. Thought most are just a little different, it doesn't hurt anything! You will find Ackley cartridges shoot tight groups! I like mine and reload anyway, just thought I would give you my thoughts on this subject. Thanks, Otis!

All the Mexican Mausers I've seen were 98's. I think there were 1910 and 1936 small rings, and one in the 1950's was large ring.

Bruce

It doesn't take a lot of horse to form cases if chambered properly. A light load of a fast powder will do it. I would try a standard load of 4895 with some 140gr bulk bullets like Powerpoints or Corelokts.

The action I have is a 1936 small ring, with "standard" M98 cocking piece (not pull knob). It has shorter bottom metal than a standard 98 though...
M~

See Dr. Howell's book "Designing and Forming Custom Cartridges" Chapter 4 pages 54-55, "Fire-Forming without Bullets"

I seem to recall a Dave Scovill article sometime back (don't have it here, don't know whether it was Handloader or Rifle) where he discussed the WSM case design in a historical context going back to the 60's (maybe even the 50's). One such experimenter's case design utilized a radiused shoulder. This is probably a stretch, but perhaps your "7x57" is a kissin cousin to this individual's design. There were a lot of experimenters back in those days, Roy Weatherby and P.O. Ackley weren't the only ones - perhaps just better known.....

Food for thought.

Kaiser Norton

Sorry, I confused Mexican with Spanish, DAH!

Gents,

This rifle isn't the product of some backyard wildcatter. I'm not saying that it isn't a wildcat, I'm saying it was done by a
pro, and that it has been to the Belgium proof house.

Now if someone will kindly tell me how to post photos on this site,
I'll post some excellent photos that I'm sure will help determine
what caliber this thing is...
Michael

Michael,

I do believe on the PHOTOGRAPHY forum are explicit instructions on how to post photos. That should do it.

GH

I have a few rifles that have been AI'd. Strangely not a one of them had the lettering fall off when the chamber dimension changed.

I do not see how pictures would help? Get a chamber cast made. It is the only way to know what you have got.

How in the world can you know when the proof marks were applied to the barrel, before or after?

To post photos, you need to open an account with a site like www.photobucket.com.

You upload your photos there, and under each photo they give you an "img" code. You simply copy it, and paste it into your post here, and it will show your pic.

Thanks to Dogcather, I'm finally in business!!! 3sixbits has a point that I hadn't considered. That the chamber was altered AFTER the caliber stamp was applied to the barrel... Anyway take a look at these photos... If it turns out to be a wildcat, I'm gonna go back to my original idea, and part the rifle out.


Thanks again for all your help!
Michael

Sharper shoulder angle on the left indicates a reformed shoulder as compared to the longer sloping shoulder on the right. I do not know why you would want to part the rifle out. You can still fire standard factory ammo as long as you like, with out trouble.. All you need is a neck sizeing die to neck size the fired brass and reload. The 7x57AI does offer two values to a shooter/reloader. One there is less trimming with the AI. Two. more powder capacity over the standard chambering.

Michael,

Just to satisfy my curiousity, I'd like to see a pic of the entire rifle. And especially the left side of the receiver. As others have said, I'd leave it as is and just get a sizing die that fits the current chambering. Likely performance would be near a .280 Rem. and that's not a bad thing...

'Course, I'm forever attracted to something different, anyway.

Grasshopper

Grasshopper-
Here are a few more pictures...



M~

Looks like a 98 Mauser large ring former military action (see finger groove for clip loading) made in Europe (see European cheekpiece). with modified bolt handle and safety. Cant tell what the scope is. Beautifully made rifle, stock is wonderful. The 7x57 AI is the 7x57Atkins Improved which is the standard 7x57 with the body straightened out and a sharper shoulder angle.
Cartridge cases can be made by fireforming standard 7x57 cases. The AI version gives you more powder capacity thus higher velocity. the AI versions work best in claw extractor actions like the Mausers, they are tough feeding in push feed models like Remington and Savage. If the barrel on this rifle is the military barrel trimmed to eliminate the steps it wil be most accurate with heavier bullets like 154 and 160 gr (like mine). If a commercial barrel it probably will be more accurate with 139-140 gr bullets.

Crazy

SJ,

Thanks for posting the pics. Beautiful rifle! Love that classic styled stock...

If you decide to form more cases, you might try seating the bullets to touch the rifling, and use a slightly reduced load. That may form the cases more fully... Good luck to you...

Grasshopper

Is the 7x57 Atkins Improved the low carb version of the 7x57 Mauser?

YEP,,,,,,,,,,,,
As opposed to 93/95 Mausers supplied to Mexico in earlier years.