My Pre-war 8x60 Mauser

[Axel E]

Of course you may use resized and shortened 30-06 brass for forming 8x60. I have done so my self many years ago before I got a good supply of RWS 8x60 cases. I simply used W-W 30-06 cases, shortened them slightly expanded the necks and ran them into my RCBS 8x60S fl die. But BE DAMM CAREFUL! As the shoulder is pushed back, part of the former case shoulder becomes part of the new 8x60 neck. As some case makes, fi RWS, have thicker walls in the shoulder than in the neck, such simple resizing may produce a “doughnut” on the new neck, effectively a much thicker case neck. Such a thicker case neck of the loaded cartridges may be enough to remove the case neck – chamber neck clearance so important to make the use of .323 bullets in .318 barrels safe. So check against the measurements of your chamber cast if there is still at least .003” clearance between cartridge and chamber neck!

[mike ford]

Of course that's a consideration. I have a large "pile"of 30-06 Match brass and use it quite a bit. I never had any problems(I checked) with reformed cases as short as 57mm( but my 6.5x57 is the rimmed version and haven't tried 5.6x57 yet). For shorter cases I would use 308(actually 7.62x51 military cases), I would expect making 22-250 cases with 30-06 would cause a problem like Axel described.I always check when I make something I never made before.
Mike

[chapmen]

However it can very well be safe to use 8x57IS(.323") in it. By a combination of variations, including depth of the grooves, the groove diameter may very well be .323"(or some diameter smaller than .323", but larger than .318").
Mike

There are a lot of "cans" in this.
Also it is possible that all the cans are on the other side- correct .318 dia......correct chamber......
In this case it wouldnt be safe.
There is an reason between .318 and .323, even before 100 years.

[mike ford]

Chapman,
I just spent an hour writing an answer explaining details of how all this came about and before I finished the power to my computer went off, and I lost it all. Now this will be a "short form" answer. During the testing for adopting the spitzer bullet, it was discovered that pressure spikes were caused more by tight chamber necks that would't allow the case neck to expand to release the bullet than by the difference in bullet diameters.They found they could open the chamber necks to allow the case to release the .323" bullet and use "S" ammo in M88 rifles. A good number of rifles already had chambers large enough, due to manufacturing tolerances. After WW1 Germany was not allowed to manufacture certain war materials,which included "S" barrels. In proofing the rifles,the bore diameter was measured and marked on the barrels. If a barrel had a 7,7mm bore, it would be marked 7,7, even if it had .323"(or larger)groove diameter.If the chamber's neck diameter is large enough to release a .323" bullet, it can be used with .323"bullets(this would be true for 8x57,or 8x60).A rifle such as this would have 7,7 / 57 (8x57I) markings, but could be used with 8x57IS ammo(or a rifle with 8x60 marking might be able to use 8x60S ammo).To determine all this, " slugging"the bore and making a chambercast is necessary, or verify that a .323" bullet will slip easily into the neck of a case fired in that chamber and not sized.
Mike

[Axel E]

Quote: There is an reason between .318 and .323, even before 100 years.

Wrong! The strict dimensional differences between I and S type barrels was only introduced 74 years ago, with the 1940 German proof law, together with all the other min/max dimesions and pressures. Have a look into 1920s-30s literature:
A 1926 dated table from the Mauser factory, published in Jon Speed “Mauser – Original Oberndorf Sporting Rifles”, page 275, shows these Mauser factory minimum dimensions of their 8x57 and 8x60 hunting rifles: bore/land 7.84 mm = .3087”, groove 8.09 mm = .3185”, clearly I dimensions by post-1940 standards. But below this table is a *footnote: “The Pirschbüchsen for the cartridges 8x57 and 8x60 are throated for the “S” bullet, so that the respective S cartridges may also be shot in these rifles.”
The RWS Schiesstechnisches Handbuch, 1st edition 1934, page 38:
„If you want to shoot the larger diameter S bullets from a barrel originally built fort he 8x57I or 8x57IR, don’t miss having a gunsmith rework the chamber’s neck area and the throat, because the unfitting cartridge will cause higher pressure.“
The 2nd edition,1940, already takes into account the new dimensions of the 1940 proof law. On page 42 ff you find a lengthy discussion on the subject with some unusual, when looked at from today, solutions:
Bolt action repeating rifles rarely had any problems when S cartridges were used in I barrels.
The problem sometimes existed with older (pre-WW1?) break open combination guns with their thin rifle barrels.
RWS’s 1940 solution and suggestions:
The “outmoded” 8x57IR cartridge will be loaded with I = .318” bullets only, no 8x57 IRS loads in the future.
The other older 8 mm cartridges, 8x57IS, 8x60, 8x60R will be loaded with S = .323” bullets only. Modern, progressive powders allowed RWS to load them to their original ballistics without exceeding the accepted max pressures when shot from an I barrel. The only remaining problem: The 8x60RS Magnum load. Here the cartridges will be marked by a knurled rim and bullet, the packages get the prominent warning: “For barrels with dimensions 7.89/8.20 mm only!”
IMHO all the I vs S problems may be traced back to Suhl and Zella-Mehlis made guns from before WW1 up to the 1920s: When the barrelmakers found out that barrels with tighter dimensions than the military M88 8.15 mm = .321” groove diameter shot the .318” I bullets more accurate, some went by the old peasant’s rule: “If a little tighter is better, much tighter should be much better!” and overdid things. I have slugged pre-WW1 “8mm I” barrels with groove diameters as tight as 8.00 mm = .315”! Even your’s truly would not dare to squeeze a S = .323” jacketed bullet through such a barrel.
Additionally some smaller gunmakers used their expensive chambering reamers, resharpened several times, as long as an 8x57IR cartridge went into the chamber. There were no set minimum dimensions before 1940, only recommendations by the industry from 1924 on. (BTW, prepared by Mauser for all the German ammo and gun makers, see the Quote above) If such a rifle with overtight barrel and/or chamber did not blow up on the proof load and did not show any damage, it was deemed OK. So I am damn careful slugging the barrel and making a chamber cast before I use any 8x57 IR drilling or combination made before 1925!

[chapmen]

I agree with all that.
For me the following points are interesting for use of .318 or.323:
chamber throat, bore, depth of rifling.
Only if this three are ok for an .323 bullett i would say it is safe.

To test an fired shell with an .323 says nothing about the three points,
because this depends on the material of the shell, and size of the chamber.

All these points are nothing to play with, and nothing that should be done with possibilitys.

If i use .323 in an .318 bore i want to be on an absolutely safe side,
if it goes wrong i am the one who is holding the gun.......

[mike ford]

Chapman,
What testing a fired case with a .323" bullets shows is if the chamber throat is ok for the .323 bullet.See Axels post above, especially the quote about using a "S" throat in a "I" chamber, so "S" ammo wouldn't be dangerous if used. Of course, if you only use .318" bullets in every thing( even "S" barrels) you will be ok as far as safety is concerned, and it might not affect accuracy very much.
Mike

[chapmen]

I think we are speaking about different things.
The diameter of the chamber throat says nothing about the the transition part.
But the transition part is the really important thing.
By testing an fired case with an .323 bullet you have points to see:
The material of the shell changes in quality from maker to maker- so every material rebounds different.
Also the wall thickness changes from maker to maker.
This works in my 6PPC, but not in an usual reamed chamber, and only with assorted and neckturned cases.
Sure it can be safe to use .323 in an "I" chambering, if all dias are ok.
But there is no general point to say it is ok without slugging and /or measuring every barrel.

[chapmen]

To be sure that we are speaking about the same:



3 is the champer throat
4 is the transition part

[Axel E]

3 is the neck area of the chamber
4 is the throat
The neck area, 3, has to be wide enough to allow the case neck of a S cartridge to expand on firing to release the bullet. This is checked by slipping a .323" bullet into a case fired in the chamber in question. If the bullet can be slipped into the expanded neck with the fingers only, the chamber neck is wide enough for the same case make with S bullets. The weak American "8mm Mauser" loads have .321" bullets and much reduced pressure, compared to European 8x57IS, to make them safe in any 8x57 rifle, I or IS.
The throat, 4, must be generous enough to allow a .323" bullet to start moving before it engages the rifling.

[mike ford]

chapmen,
The point Axel and I both are making is the fundamental importance that the bullet be able to start moving from the case without being impeded. As an example, take your 6mm PPC. Even if you use a .243" bullet in a case that has been properly formed and neck turned and fired several times w/o incident, if it stretches enough to jam into the throat, it may prevent the bullet from moving until the pressure gets high enough to overcome the impedance. With modern progressive burning powder, this early pressure causes the powder to burn even quicker and increase the pressure even more. On the other hand, if you use an oversize bullet (say a .245" British bullet), but the case releases it, it shouldn't create a problem because the bullet is moving and creating more volume as the pressure is building up.Once the bullet has traveled in the barrel, the length of the bearing area, it has been sized to the diameter of the barrel. Or if a case slips through w/o being neckturned a similar condition can occur with the first firing. All this is not something that is dependent upon "S" or "I" bullets or barrels, it's just that they create most of the questions.
Mike

[chapmen]

Okay, there are different ways to get to the goal.

Because i am always make an chamber cast for measuring i have no need to try if an .323 bullet will fit an fired case, for me this is an basic to check this .

Btw. : i havent measured any chamber that was too small in the neck area too accept an .323 bullet and release it free.

Maybe its oversized, but if i have bore dias like .320 i size down .323 to .320-.321.

One of my mausers , proofed 1923, have an bore dia .320, there was no way to get accurary with .318 ore .323 bullets.
After sizing to .320 it shoots perfect.

Every rifle and barrel is an individual......

[mike ford]

chapmen,
Of course the standard "school solution" is to advise an owner to make or have made a chambercast.However a great many owners don't understand what a chambercast is, have any cerrosafe, or have accurate enough measuring tools( a yardstick just won't do). In the case of 8mm rifles,the questions and probable answers are so familiar that testing a bullet in a fired case is just a very quick and simple test anyone can do w/o having to go through a lot of "who struck John" to get a practical answer ( a great many other rifles do require a chambercast, and slugging the bore, to determine what they are).BTY, instead of sizing .323" bullets, you might give give 32Win.Spec. bullets(.321") or commercial 8mm Mauser ammo bullets(Rem. is .3215") a try. I presume by "bore dia .320", you mean groove diameter. As has been previously said,most "I" barrels do have .320-.321" groove diameters.
Mike

[chapmen]

The thing what for me is very interesting: What do you fire in an unknown 8mm? If i follow this, the not so understanding owner takes an IS .323, fire it, and then proofing if an.323 bullet will fit the case?????? This could maybe the first and also the last shot.
But everyone shut decide by himself whats safe and not.
I do it my way, and i feel safe.

[mike ford]

Chapmen,
Of course, you should always do what makes you feel safe. At first, if I have a question, I either fireform a case, fire an American 8mm Mauser cartridge, or a handload with a .318 bullet, to get a case to check with.
Mike