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Sauercollector
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Small Ring Conversion questions_1
      #152798 - 04/02/10 07:16 AM

Hi All. First post here. I have a SMALL RING Sauer-Mauser in 7 x 57 that I am considering rebore and chamber to 9.3x64 Brenneke (Not 9.3 x 62) I have consulted with a reboring outfit and they tell me it can be done but would need some work on the feed ramp and opening of bolt face etc. Back story on this rifle is this: This is an early four digit s/n's Mauser 98 (Sauer Mauser) rebarreled to 7 x 57 in Germany in early 30's. (Originaly this Sauer-Mauser was likely 8 x 57J) Barrel has the intergral rib in (7 x 57) but the bore is crap. Barrel muzzle end measures .590 Dia. Question is can this 9.3 x 64 conversion be done safely on a small ring Mauser? Should I be concerned about strength of the small ring action with said conversion? Can anyone reccomend twist rates for this project? (Bullets up to 300 gr) Thank you in advance, Jeff

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Bramble
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Re: Small Ring Conversion questions_1 [Re: Sauercollector]
      #152816 - 04/02/10 11:36 AM

It is really not recommended practice to go above 8 mm in a small ring action. That is not to say it has not been done, but I would not build one and sell it to you.

If you go to this link at the moment De'Haas book is online and is a good read on Mausers while it is there. I am sure you can save the pages but I won't and post them because it is copyright.

http://books.google.co.uk/books?id=tuVUM...;q=&f=false


Regards

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dons
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Re: Small Ring Conversion questions_1 [Re: Sauercollector]
      #152855 - 05/02/10 12:07 AM

The 9.3 Brenneke produces a high chamber pressure, somewhere north of 54,000. I would not feel comfortable with a small ring 98 in this caliber.

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kuduae
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Re: Small Ring Conversion questions_1 [Re: dons]
      #152897 - 05/02/10 09:13 AM

There is some demand here in Germany for the small-ring Kar98a actions for building slim, light repeating rifles, but caliber choice is usually limited to cartridges up to 9.3x62, not for lack of strength of these small-ring actions. The recoil of a 9.3x64 or a 8x68 will be awful in a light, slim rifle, and for a rifle with enough weight for such cartridges you may use a more-frequent large-ring action as well.

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

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Altamaha
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Re: Small Ring Conversion questions_1 [Re: kuduae]
      #152965 - 06/02/10 07:51 AM

To show how nice a standard length M98 works with the 9.3x62, I took a couple of photos.

Top photo shows the cartridge in the well of a 1909 Argentine action.

Bottom photo shows the cartridge in the well of a Small Ring 1936 Mexican action.

Regretefully I do not have a small ring KAR action for comparison!

Note that the magazine box projects into the well and shortens the available COL by about 1/8”.

My choice? The full size 98 style action, not only for the magazine length available but also for the increased strength.

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kuduae
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Re: Small Ring Conversion questions_1 [Re: Altamaha]
      #152970 - 06/02/10 08:21 AM

Well Altamaha, I have never handled a Mexican small ring action, but from your photos I guess the Mexican action is not only small ring. From the position of the extractor collars it seems to be an "intermediate" action too, the bolt about 5mm = .2" shorter than the standart large ring M98. The Kar98a actions used by the German gunsmithes post-WW1 are of the same length as the large ring Gew98 actions, so the magazine length limitations do not apply. So I would use these for any cartridge in the diameter and pressure range as the original 8x57S cartridge, that is the hot European CIP pressure loads, but not for any "Magnum" pressure cartridge, be it belted or rimless. So for me the 9.3x62 would be "in", the 9.3x64, 8x68S, 6.5x68 and all American Magnum cartridges "out".

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

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Altamaha
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Re: Small Ring Conversion questions_1 [Re: kuduae]
      #152972 - 06/02/10 08:36 AM

Well I am not very knowledgeable concerning small ring actions! I have Kuhnhausen's book "The Mauser Bolt Actions" that has most of the actions listed with dimensions. I will do some research and see what he calls it.

I like the small Mexican action, I am thinking of building a 7x57 on it.

Just checked the book, you are correct, it is an intermediate.

Edited by Altamaha (06/02/10 08:38 AM)

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tophet1
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Re: Small Ring Conversion questions_1 [Re: Altamaha]
      #152976 - 06/02/10 09:51 AM

Welcome to Nitro Express sauercollector.

7x57 or any of the 57 family sounds like a good idea.

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kuduae
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Re: Small Ring Conversion questions_1 [Re: tophet1]
      #152978 - 06/02/10 11:15 AM

A little bit of basic physics: A cartridge case contains pressure. Said pressure works against the action's breech only by the base area of the cartridge case. The case works like a piston against the breech. A bigger diameter case, having a larger base area, exerts more strain on the breech at the same pressure. The length of the case or the diameter or weight of the bullet has no relevance here, as it is contained by the barrel. As the 7x57, the 8x57IS and the 9.3x62 share about the same base diameter and the same allowable pressure of 3400 bar according to international CIP rules, so they put the same strain on the action. The 9.3x64 has a max allowable working pressure of 3800bar working on a much larger base area, so it puts a much higher load on the breech. The pressure is only increased by about 10%, but it works against a much larger base area too, so the load it puts on the action is increased by about 25%. Another example: The .223 Rem has a pressure of 3700bar, the .416 Rigby only 2850bar, but the Rigby has several times the base area that makes the pressure work against the breech, so the load applied by the Rigby case is much higher than that of the .223.
This is the reason why I would put the 9.3x62 in any action suitable for the 7x57 or 8x57IS, but not cartridges of higher pressure and/or larger base diameters. Otto Bock designed the 9.3x62 this way in 1905!

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

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Altamaha
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Re: Small Ring Conversion questions and Chamber Pressure [Re: kuduae]
      #153014 - 07/02/10 01:34 AM

Kuduae, you are correct on pressure exerted on the bolt lugs and few realize this important factor.

I was in the midst of designing a 50 BMG action in 1995 and "discovered" the proper manner in which to calculate bolt lug shear strength and the forces generated by various cartridges on the bolt lugs. I obtained the cartridge case rear area by sectioning cases and precisely measuring for calculations.

I "built" an Excell Spreadsheet to calculate the shear strengths of various actions, and the resulting force generated by many of the big bore cartridges at various chamber pressures.

If anyone is interested I will post the data calculated, it is extremely interesting to a big bore rifle builder.

I also have used the Oehler M35 Velocity and Chamber Pressure system. This instrument has given me valuable insight in what is real and what is false concerning cartridges and pressures.

Edited by Altamaha (07/02/10 01:39 AM)

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Grenadier
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Re: Small Ring Conversion questions and Chamber Pressure [Re: Altamaha]
      #153015 - 07/02/10 01:48 AM

True regarding force exerted by the base of the bullet and that the force is applied to the lugs.

However, if one removes metal from the feed ramp, and if one removes metal from the front portion of the action opening to allow for a longer magazine to be fitted, then the amount of metal supporting the lower lug is reduced and the action is accordingly weakened. Many standard length mausers have been converted to shoot .375H&H and other long magnums with varied success and some consider the practice of removing metal from the lower front of the action acceptable. Nevertheless, if you remove metal from the area of the action that supports the bolt lugs then you have a weaker action and that is not the best way to go. The proper thing to do is to chamber an action for a cartridge comparable to one for which it was originally designed. That's why mausers were made in different sizes.

--------------------
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Altamaha
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Re: Small Ring Conversion questions and Chamber Pressure [Re: Grenadier]
      #153021 - 07/02/10 03:13 AM

True again Grenadier.

I have an original Whitworth 375 H&H built in Manchester on a Mark X Mauser action. The bottom lug is ground half away!!!!! By the maker at Manchester!! A big no-no. I reserve it for Factory loads and mild cast bullet loads, true it likely will never fail, but I just do not relish the lack of metal in the bottom lug. With the Mark X actions, there is enough metal in front of the trigger to lengthen the magazine to the rear, instead of the front, I wonder why gun makers do not realize this.

This is why I like the CZ550 and the Brno602: Lots of room in the magazine well!

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DarylS
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Re: Small Ring Conversion questions and Chamber Pressure [Re: Altamaha]
      #153042 - 07/02/10 06:26 AM

You can always reduce bolt thrust, ie: pressure on the bolt, by going to an Improved ctg. design. The straighter the case walls, the less the breech pressure.

The 9.3x62 has very close to an 'improved' case design, ie: minimal taper. It's design was way ahead of it's time.
Check out the something like .474" head diameter (mine is .472" - only .002" larger than sammi standard for the '06 etc.) Check out the .454" shoulder, same as most Improved cases on the .470" head cases.

The 9.3x62 has identical capacity as my .375/06IMP that is cut oversize for normal - .472" head, and .460 shoulder. Both have a 78gr. capacity.

The Improved cases are the safest for loading in any action of questionable strength. The .308 family of ctg. follow this basic improved design of minimal taper as well, but have shorter bodies, which stick less well than longer ones in the chamber during pressure peaks.

Ctgs. of greater taper, like the .416 Rigby show pressure signs of bolt thrust/sticking long before better designed, straighter brass does, as the sloping case is less able to grip the chamber walls until pressure subsides, therefore they have and are only capable of lower working pressure limits.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

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Altamaha
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Re: Small Ring Conversion questions and Chamber Pressure [Re: DarylS]
      #153044 - 07/02/10 06:50 AM

Daryl Wrote:

"Ctgs. of greater taper, like the .416 Rigby show pressure signs of bolt thrust/sticking long before better designed, straighter brass does, as the sloping case is less able to grip the chamber walls until pressure subsides, therefore they have and are only capable of lower working pressure limits. "


Do I ever agree with this! Found this fact to be very true when working with the Oehler M35 System testing the 416 Rem and a 416 cartridge of my design with straighter walls.

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kuduae
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Re: Small Ring Conversion questions and Chamber Pressure [Re: Altamaha]
      #153098 - 08/02/10 03:23 AM

Well, the .416 Rigby a tapered case with a sloping shoulder? I have not yet seen a case with less taper and a sharper shoulder angle, I see very little possibility of "improving"it! BTW, the 9.5x57Mannlicher-Schoenauer aka .375NE shows even less taper than the 9.3x62.
As I told above, there is no need to open up any standart length Mauser 98 action or magazine to handle the 9.3x62! This cartridge was designed "taylor-made" to use the available magazine length of the standard military 8x57S actions to it's capacity. Of course, if you want to use longer than standrd bullets seated out you better use a true Magnum length action from the start! The opening-up of standard length actions for cartridges like the .375 H&H, even by factories like FN or Parker-Hale, is nothing else than a makeshift expedient to avoid the cost of making a true magnum length action.

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

Edited by kuduae (08/02/10 05:17 AM)

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Sauercollector
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Re: Small Ring Conversion questions and Chamber Pressure [Re: kuduae]
      #153122 - 08/02/10 06:34 AM

Hi everyone! Thanks for the excellent information that you all have contributed to this thread. I just measured the cartridge box opening on my small ring action and it measures exacty 3.270" (83.058 mm) Very similar to the action shown in the top/upper position in the two posted photos. So as I read the thread, I understand that the 9,3 x 62 Conversion on a small ring action is possible with out too much hassle or work? (Please confirm)

A bit more info on the rifle. According to original proof info (2,4g G.M.B ST. m. G.) equates to 8x 57J (.318 bore). Mauser S/N is 1125 and Sauer S/N is 89057. Double Set Triggers. Looking at the action with the stock removed, I see no indication that the action was ever case colored, as seen on some Sauer-Mausers. Rifle has Sauer type single foot claw mounts numbered 490 (likely to match orginal scope which is long gone) Barrel is octogon to round with one fixed rear sight and one flip up sight. Barrel, as noted in begining of this thread is currently 7x57 proofed in "532" (May 1932) Barrel has the "BUG" proofs and action has the "BU" proofs.

On another note. Anyone have a set of single foot claw rings that they would like to find a home for????

My intent with the rifle is to re-bore and chamber, case color frame and small parts and restock in Turkish walnut; A piece which I already have. I appreciate all of your help and insight on my project and from time to time may post photos as the project proceeds as time and budget allows. JeffS.

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tophet1
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Re: Small Ring Conversion questions and Chamber Pressure [Re: Sauercollector]
      #153125 - 08/02/10 07:36 AM

Jeff, we all enjoy watching a project come together. Definantly keep us posted. Edit: There are quite a few 9.3x62 fans here as well as a mine of info. Just do a search.

Edited by tophet1 (08/02/10 07:37 AM)

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kuduae
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Re: Small Ring Conversion questions and Chamber Pressure [Re: tophet1]
      #153127 - 08/02/10 08:22 AM

With that early Mauser commercial serial number and being a small ring action, you have probably got an early rare "transitonal" action instead of a Kar98a one. Jon Speed lists transitional actions up to serial # 3209 of Mauser's commercial serial numbers. according to his list the action #1125 is dateable to 1899. Can you please post a photo of the boltsleeve. It should still lack the bolt sleeve lock on the left side. But I would still not hesitate to rebarrel it to 9.3x62.

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

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Sauercollector
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Re: Small Ring Conversion questions and Chamber Pressure [Re: kuduae]
      #153181 - 09/02/10 05:32 AM

Hello Kuduae. I suspected that my Sauer-Mauser maybe one of the early transitional actions. I have read a bit about them in Jon Speeds book but do not yet know enough about Mauser 98's to say with any definitive authority that it is one of these actions. I will post photos but right now do not know how to do that. If someone is willing to talk me through the process, I will make an effort to do so. Thanks for your help!

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Sauercollector
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Re: Small Ring Conversion questions_1 [Re: Sauercollector]
      #153343 - 11/02/10 12:10 PM









A few photos of the Sauer-Mauser Small ring 89057/1125 and one possible blank choice. Can anyone tell me if this is a "transitional" action? Thanks in advance!

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dons
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Re: Small Ring Conversion questions_1 [Re: Sauercollector]
      #153347 - 11/02/10 12:57 PM

The serial numbers along with their location, and the bottom metal lead me to conclude that this is not a transition action.

Edited by Dons (11/02/10 01:01 PM)

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mauserand9mm
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Re: Small Ring Conversion questions_1 [Re: dons]
      #153351 - 11/02/10 01:34 PM

Getting back to the physics (earlier in this thread), consideration should also be given to the additional force of the reaction of the projectile and powder being accelerated down the barrel (evident as recoil). I did some calcultaions for a 308Win and the acceleration force can add another 20% on top of the force from the pressure alone.

So even if the case head is the same diameter and the pressure is the same between two cartridges in the same action type and size, the cartridge with the heavier recoil will exert more force on the action.

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DarylS
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Re: Small Ring Conversion questions and Chamber Pressure [Re: kuduae]
      #153388 - 12/02/10 02:36 AM

Quote:

Well, the .416 Rigby a tapered case with a sloping shoulder? I have not yet seen a case with less taper and a sharper shoulder angle, I see very little possibility of "improving"it! BTW, the 9.5x57Mannlicher-Schoenauer aka .375NE shows even less taper than the 9.3x62.




"Well, the .416 Rigby a tapered case with a sloping shoulder."

Sorry about that - I meant it had a grossly tapered body, not the shoulder. It has a quite sharp shoulder, but way more taper in the body than needed. It is an antique design meant to provide extraction when unstable, temperature sensitive powders were used, ie: cordite. Since we've become familiar with improved design cases, we've learned that the straighter the case, the easier the extraction as bolt thrust is reduced greatly when high pressure is encountered. My new .375/06IMP, with 78 to 81gr. capacity depending on case make, exceeds 1912 .375 H&H ballistics by 70fps with 300gr. yet the cases literally fall from the chamber with "0" pressure signs. It has a mere .005" per side, taper.

The 9.3x62 has .019" total taper, or .0095" per side. This was measured on 2 fired cases from a Sauer rifle fired with factory Sako ammo. My own 9.3x62 Mauser, made in the 1920's, shows .472" base and .454" shoulder, for .009" taper per side. I'd say that is about even with the 9.5x57.

The .416 Rigby has .050" total taper, or .025" per side.

Yes, I am aware the 9.5x57/56 MS (as per COTW) has a mere .0095" taper per side - which is a very good design.

As to 'improving' the Ribgy, removing that gross .025" taper is what 'improving' the case shape is all about. Except for the taper, is very close to a beltless .416 WTBY(or visavis), only with a lot more taper. It would be a simple matter to improve that taper.

Now, whether incresing it's capacity and therefore velocity will improve it's killing power, is merely an argument over whether the .416 WTBY possess better killing power than the Rigby as it is now. With less taper, the Rigby will duplicate the WTBY.

The WTBY possesss the same taper as the 9.3x57MS & 9.3x62 - only .010" per side, btw.

--------------------
Daryl


"a gun without hammers is like a Spaniel without ears" King George V

Edited by Daryl_S (12/02/10 11:08 AM)

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kuduae
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Re: Small Ring Conversion questions and Chamber Pressure [Re: DarylS]
      #153392 - 12/02/10 03:38 AM

Sorry, Dons, but this really is an original Mauser commercial transitional action! Why:
First photo: There is no bolt sleeve locking plunger or it's housing on the left side of the bolt sleeve! This alone says it is not a "full developed" M98 action. Also note the long commercial firing pin nut and the teardrop shape of the bolthandle.
Second from top: You can see the Mauser serial # stamped at right angle to the receiver behind the recoil lug. This is Mauser's typical location for the serial # as stamped on all commercial actions sold as "action only" or "barreled action" to other makers like S&S, Rigby, H&H or Westley-Richards!
Photo 4: here I can make out the typical location of the Mauser # on the top rear wall of the magazine. More often than not these serial numbers and their location are the only means to identify a commercial Mauser Oberndorf action used by other gunmakers.
Photos 2,4,5: Here you see the typical Mauser factory set trigger arrangement with it's housing machined integral, no separate housing. Also note Mauser's long set trigger mainspring. All aftermarket dst arrangements used a separate housing, pinned to the triggerguard.
Photo 2: Early Mausers all came from the factory with the military floorplate and release. The Suhl gunmakers often reshaped the larger-than-military trigger guard and they first installed the floorplate release lever, only later adopted by Mauser and perfected with a hinged floorplate.
All in all, this is a typical example of an early commercial transitional action!
I strongly recommend reading Jon Speed's "Mauser Original Oberndorf Sporting Rifles"!
BTW, I know a very early 9.3x62 on an identical Mauser transitional action with the same bottom metal treatment. As it is the typical pre-WW1 Suhl style with ribbed,half-octagon barrel, side-clips and wedge schnabel foreend,fully engraved, probably made in, at least proofed before 1912 in Suhl, but retailed by W. Foerster, Berlin. It is still going strong after 100 years!

--------------------
German foresters: We like sustainability! For merely 300 years by 2013.

Edited by kuduae (12/02/10 04:07 AM)

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450_366
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Re: Small Ring Conversion questions and Chamber Pressure [Re: kuduae]
      #153394 - 12/02/10 04:18 AM

Now i feel stupid, i only see an ordinary mauser.

Could someone please make some arrows on the pictures to point out the difference.

--------------------
Andreas

"Yeas it kicks like a mule he said, but always remember that its much worse standing on the other end"

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