Hi all have slight problem and wondering if anyone can help me.

Recently purchased what i thought was an 8x57 small ring mauser 98. upon firing factory 8x57 got a surprise. Body taper dissapeared and the shoulder of the case is now aprox 40 deg or 30 deg. neck is now longer as a result. here are some of the dimensions.

Case leangth 2.225"
Shoulder diameter .440
Base Diameter .465
Neck Leangth .325

Any help would be apreciated because ive been scratching my head for hours my first thoughts are ackley improved but i cant find any specs. Is there another improved case style that it might be?

Maybe an 8mm-'06??

If not an 8mm-06 it may be an 8mm x 60mm instead of 8mm x57mm.

Regards,
Gene

It's probably best to have a chamber cast made so you have something to fully measure. Years ago, every gunsmith worth his salts had his version of an "Improved" cartridge. It seem s they were all different and yet, pretty much the same as well. Chamber casts are still pretty inexpensive and worth the knowledge you'll gain. If it's an odd chambering and you need to reload, try a Hornady Universal necking die in 8mm (If you'll only be shooting them in one rifle ). They're cheaper than full length dies and work really well. HD1

What you have is an 8x57 with the shoulder blown-out from .431 to .440. All of your other measurements are 8x57, but some are a little off. This is not unusal for an old military rifle.

The case is a little short and the neck a little long. You may want to check your measurements and verify for accuracy.

I would have it checked-out by a good gunsmith. If it is OK then fireform your cases, neck size them, load up (starting low & working up) and head for the rifle range. You could start at the lowest book load for the 8x57.

Later today I will compute your new case volume and post it here.

Good luck,

Nitro

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Nitro

Garand Collectors Assoc.
NRA Life Member
SASS #36461

Is definatly not 8mm 06 or 8x60 a 8x57 round chambers with slight resistance on the bolt.
Measurments are accurate i tripple checked them as i said only thing that comes to my mind would be ackley but i think it may have to much taper for the ackley form. Any ideas as to what velocities i might be looking at with 175 grain sierras.

If you have the water capacity of a fired case, a program like Quickload can be a big help in determining load data, at least to start with. Failing that, if you have water capacities of a standard 8x57 case, and then perhaps neck up a .30-06 case to 8mm (and measure the water capacity), this too will give you a good idea of where to start. I think that Nosler has 8mm-08 load data, or at least they used to.

You don't want to get carried away interpolating load data, but if you have several examples that are very close, and something in the middle, you can make good educated guesses as to things that will be safe to start with.

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MikeG

If I chambered an 8mm57 to Ackley's version of an improved chamber I would expect a case as you have described after firing. The neck on an improved chamber is longer than the neck of standard chamber (parent).

Resistance to chambering: If done correctly the barrel is set back when going from a standard chamber to an improved chamber, this is the only way all of the original chamber is removed, when the short cut is taken all of the original neck is not removed because it is shorter than the improved neck, therefore if the barrel is not set back there will not be belt resistance when chambering a round.

Most small ring Mausers were 7mm57 with the exception of an early carbine, it had a small ring/large shank, this combination made the receiver thin, thinner than the 03 Springfield.

Three chambers that benefited from the Ackley improved chamber: 30/40 Krag in any rifle except the 30/40 Krag, 257 Roberts and the 7mm57. The 8mm57 would get the same benefit as the 308W with the increase in the diameter of the powder column, the caution here is the small ring.

When fire forming the case should be expected to shorten, it is not likely you measured the length of the case before firing, by the numbers it would appear the case is shorter by .015 thousands, this happens when the case expands to fill the chamber the neck is pulled back.

Fire forming in an Ackley chamber, if chambered correctlu the neck is formed (sized) when the cartridge is chambered, the case and shoulder is blown out and formed when fired.

F. Guffey

I measured a case fired from one of mine with an original barrel. Neck length is .340, shoulder angle is 68 deg. approx. ,shoulder dia. is .436 , base dia. is .466 , case rim dia. is .466. , case length is 2.244.

I don't understand your measure of "shoulder angle"?
The nominal shoulder angle of either an 8x57 or 8-06 is less than 20 degrees.


Also, the diameter at shoulder of an 8x57 is 0.431" - an 8-06 is 0.441".


You either have a over-sized military chamber or an improved cut chamber. Either way, it looks like an 8-06 reamer would clean it up! But, check the magazine to see if its long enough for a 30-06.

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Ray

Wyoman, the angle of the shoulder is 20 Degree 48'. when measured one way or 69 degree 12' when measured another way meaning the angle between horizontal and perpendicular is 90 degree. In my opinion that was a good guess, and there is nothing to be alarmed about, the difference between your fired case at the shoulder and a sized case looks to be .003 if measured from the same place listed in diagrams.

F. Guffey

I know what mine is, I was giving him something for comparison.