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Old 11-29-2009, 11:58 PM
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8x57 improved?

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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?
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Old 11-30-2009, 04:30 AM
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Maybe an 8mm-'06??
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Old 11-30-2009, 04:39 AM
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If not an 8mm-06 it may be an 8mm x 60mm instead of 8mm x57mm.

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Old 11-30-2009, 07:10 AM
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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
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Old 11-30-2009, 12:17 PM
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8x57 Improved

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,


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Old 11-30-2009, 06:20 PM
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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.
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Old 11-30-2009, 06:37 PM
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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.

Originally Posted by faucettb
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Old 12-01-2009, 02:21 AM
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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
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Old 12-13-2009, 07:13 AM
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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.
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Old 12-13-2009, 04:32 PM
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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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Old 12-17-2009, 04:23 AM
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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
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Old 12-17-2009, 06:30 PM
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I know what mine is, I was giving him something for comparison.
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Old 10-06-2013, 05:49 AM
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8X57MM Ackley improved

Is what you have. A great conversion for short action {Yugo's} Mausers. Shoot regular 8x57 MM to fire form and then reload with the improved dies which can be special ordered. Will just about duplicate a 06 in ballistics. Shoots best with heavy bullets as rifling in Military 8x57's was cut for 190 grain to 200 grain bullets. To fast for most lighter weight bullets. My experience.
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Old 10-06-2013, 09:46 AM
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What is stamped on your Receiver

Parko, What is the stamping or crest on your Mauser's receiver? You may have something which has been rebarreled. Secondly, how long is your barrel, and is it still the stepped military one?

FWIW, I have come to the conclusion that an improved 8 x 57 is better in a stepped barrel than my 8 x 06 is. You will lose three inches of barrel length, with either, compared to a true sporting chambered 8 x 57 Mauser. But you still pick up about 150fps. over the original.

All of the Speer 8mm bullets were made for 50,000CUP loadings. The quick riflings deal with the lengths of the bullets, not the weights, so a long spitzer 154 gr. Hornady, equals a heavier R.N. slug in length. The longer military throat is a separate problem, which adds free bore where its not needed. More so with the newer spitzers.

With one of these powerful rounds chambered into a small ring action, I would have a gunsmith carefully check your head space. The previous owner may have stretched the receiver ring a bit. This is why I hope you reply back here, with the Crest info on top of your receiver ring.

The funny thing about our U.S. commercial 8 x 57 Mauser ammo is that while its downloaded to about 32 Win. Special specs, it still penetrates in flesh the deepest of any common soft point bullets, in this cartridge. Faster means more slap, but not as deep. I've never shot the Euro commercial ammo, so I won't hazard any guesses.

There are now about four or five 8mm bullets made for the 8mm Rem. Mag. and the 325 WSM, which are really tough customers. Add this to the Barnes copper and gilding metal homogenous bullets and you can do anything with your rifle, at least here in the lower 48. The laugher here is the 325 WSM, as Winchester warns not to use it on N.American D.G., because of potential jamming problems. I'm guessing that your imp. Mauser will feed like greased lightning, but you should check that one out, also.

One bugbear though, is that some back yard G.S.'s would merely cut a blank shoulder on the end of the barrel threads, when they set a barrel back. Some felt that leaving 5 or 6 threads would suffice for holding certain cartridges. IMO, this is where things can go South, with the newer powders, and some older reloading manuals. You have to pull the barrel off, to check on this possibility. Different models of M-98's have different steps, so you can't look at gaps in the barrel to wood contacts, as the barrel may have been replaced with one from another model. Back in the day, G.S. 's would hoard take off Military barrels, if they had good sharp riflings. A lot of perfectly good 8mm's became 270 Win.'s in this way.
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Old 10-06-2013, 06:22 PM
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This thread is coming up on 4 years old...kinda doubt Parko is still around.
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Old 10-07-2013, 08:00 AM
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slooow thread

I didn't backtrack before I answered this thread. Broom, you're right, its older, and only about four answers deep. OTOH, these threads are more and more searchable on the net, as time goes by. We probably won't hear back from Parko, so that part will remain a mystery.

But both the small rings and some of the large ring Turks, share some of these same small barrel shank, shortcomings. Adding into the mix, some back yard gunsmiths, who felt 5 or 6 of the Mauser's 7 threads were enough to hold their rifle's head space, with some of these cartridges, and this thread may keep someone from going off the reservation.

Both these small ring jobs and the ubiquitous 7.7mm Jap Arisakas leave the door open for catastrophic failures. Fewer thread turns on a small shank Mauser, or threading a replacement barrel for an Arisaka with 1 in 12 American threads, and crabbing the barrel into its metric threaded receiver, can lead to blowups which can't be predicted by just looking at the rifle, beforehand, or even using head space gauges.

This latter problem, caused such consternation that my 1947 Logan 11 inch lathe's quick change gearbox has the 1 in 11 pitch included. the 7.7mm Arisakas were about the only 1 in 11 thread pitch, around after WWII, to require this mod.

Both the Mausers and the earlier 6.5 Arisakas, had common American thread pitches, and these never caused any problems. But Mauser's thread patterns are still a bone of contention, in today's replacement barrels. The Howas, Vanguards, ect. are also a weird metric pitch, and my G.S. keeps a dedicated metric lathe, set up against a back wall, in his shop, just for these overseas, metric jobs.
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Old 10-07-2013, 08:46 AM
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old thread, but I notice that no one mentioned that there are a number of IMPROVED 8x57, no just the Ackley. After the world lots of local gunsmiths made their own improved versions of the 8x57. the 8x57 Flaig Improved comes to mine. I see a few of these strange ones at gun shows. The specs for these have long since need buried. chamber cast!
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