Planning out a 10.75X68 build

[sestoppelman]

Yep, with todays better bullets and powder choices, that old round is a way better round than in Pondoro's day, just like many others are. I have more than once looked for one myself. Go for it!

 

[WebleyGreene455]

View attachment 347375
The gaur bison in this photograph was hunted in a shikar in 1964 . My good friend , Riaz Sharrif ... Who is the author of "Ekti Shikaree Er Jibon Er Obhiggota"
( " The Life Experiences Of A Professional Shikaree " ) , was the professional shikaree who guided this shikar .

The 2 rifles in the photograph ( belonging to the 2 clients ) are a .348 Winchester calibre Model 71 lever rifle ( Left ) and a .423 Mauser calibre Fabrique Nationale Mauser 98 action bolt rifle ( Right ) . It took the clients 16 shots with the .423 Mauser calibre rifle to dispatch that 3000 pound bull gaur bison . They also shot it 9 times with the .348 Winchester calibre lever rifle ( right ) . The ammunition used was German RWS brand 347 grain solid metal covered cartridges .

Certainly not a dangerous game calibre ... by any stretch of imagination .

Now , to put matters in to perspective ...
My former professional shikaree partner , the dearly deceased Tobin Stakkatz also used to own a Fabrique Nationale Mauser 98 action bolt rifle chambered in .423 Mauser calibre . He would use this rifle to devastating effect against our 300 pound West Bengal Bush Boars ( Most of which , average at 300 pounds ) .

He killed at least 20 of the 63 Bengal Bush Boars harvested during 1 of our Kooch Bihar Bengal Bush Boar culling programmes ( Pictured below ) .
View attachment 347376

Major, forgive me if I missed this one elsewhere. I'm guessing the guar has plenty of thick, hard muscle plus a strong hide that basically act something like sandbags and slow the bullets down considerably before they get to the vital stuff? Do they have the same sort of "trample the perceived threat into the ground now, realize it should be dead later" response that a African buffalo has?

 

[One Day...]

And herein lies the secret...

... of successful Mauser custom buildups, chren.

There is a pretty darn good reason why Mauser offered 20 (!!!!) different actions, and that reason is not the bolt face diameter nor the action length.

The reasons are:
1) the cartridge geometry in the magazine, therefore the width of the magazine box;
2) the feeding rails gap and profiling;
3) the feeding ramp angle;
that need to be exactly matched to the diameter and length of the cartridge for the rifle to feed reliably.

Many "gunsmiths" have taken liberties with this. Heck, as long as the action is long enough everything is good, right? No it is not...

 

[WebleyGreene455]

And herein lies the secret...

... of successful Mauser custom buildups, chren.

There is a pretty darn good reason why Mauser offered 20 (!!!!) different actions, and that reason is not the bolt face diameter nor the action length.

View attachment 347432

The reason is the cartridge geometry in the magazine and the feeding rails profiling, that need to be exactly matched to the diameter and length of the cartridge for the rifle to feed reliably.

View attachment 347433

Many "gunsmiths" have taken liberties with this. Heck, as long as the action is long enough everything is good, right? No it is not...

I am intrigued by the fact that there is an apparent difference between the "No. 3 for 8x57mm" and the "No. 11 for 9.3x62mm". I was under the impression that a 9.3x62mm cartridge would load and feed just fine in an unaltered 8mm action.

 

[One Day...]

Different LENGTH. Same issue as between .458 Win and .458 Lott. The relief (i.e. widening) in the feeding rails needs to be in a different place with shorter or longer cartridges.

I am not a specialist of the M98 action minute but critical differences, others are to whom I happily defer, but I believe that both 8x57 and 9.3x62 were built on the Standard action. The 9.3x62 is only 0.12" (1/8th") longer than the 8x57 (3.29" vs. 3.17"), so I will speculate that the rails profiling and relief position, as well as the ramp angle would be different between No 3 and No 11 actions.

We are used nowadays to think in terms of standard length vs. magnum length, but Mauser actually offered 3 action lengths: Kurz: 8 ¼”, Standard: 8 ¾”, Magnum: 9 ¼”.

 

[Major Khan]

Major, forgive me if I missed this one elsewhere. I'm guessing the guar has plenty of thick, hard muscle plus a strong hide that basically act something like sandbags and slow the bullets down considerably before they get to the vital stuff? Do they have the same sort of "trample the perceived threat into the ground now, realize it should be dead later" response that a African buffalo has?

Oh definitely , Webley . The gaur is the most difficult to dispatch ... among India's " Dangerous 6 " . This is because the gaur has EXTREMELY thick muscles . Think of them as ... the body builders among the bovines , or the Arnold Schwarzenegger of wild cattle . They are also extremely unpredictable ... in terms of behavior .
If a gaur comes across a human being , it will either ( by way of COMPLETE randomness ) :
> Flee from the human beings .
> Ignore the human beings
> Attack the human beings , ON THE SPOT
> Pretend as if it is moving away ... only to circle around the human beings , flank them from behind and THEN attack them .
Even though I have no experience with African Cape buffalo , my reading seems to indicate that most African Cape buffalo average about 1300 pounds in weight .
By comparison ... A fully grown bull gaur can weigh anywhere from 2000 pounds to 3000 pounds .
Here are 2 of the 15 bull gaurs ... which I have personally dispatched , to put matters in to perspective .

Here is 1 dispatched by a client of mine .

 

[Brian Rothhammer]

> Mannlicher Schoenaur ( purpose built , because this pattern of rifle does not easily lend itself to re chambering ... thanks to the rotary magazine ) .

 

[WebleyGreene455]

Different LENGTH. Same issue as between .458 Win and .458 Lott.

Looking at my Kar98k's mag box, I would think there was sufficient room for the 1.6mm difference in OAL between 8mm and 9.3x62mm, compared to the 7+mm difference in OAL between the .458 Win and .458 Lott. But I expect some slight modification to the feed rails might be needed for a conversion between the two German calibres.

But on the subject of the 10.75mm Mauser, gaze upon this (not mine):
Pre-WW2 Mauser Oberndorf sporting rifle. Military style 98 Mauser receiver marked on the left side "WAFFENFABRIK MAUSER-OBERNDORF A/N". Crown/B, U and G proofs. Top of barrel is retailer marked from Kenya "Chas. A. Heyer & Co. Nairobi".

 

[Major Khan]

Beautiful pieces of art , Mr. Rothhammer . I myself have only ever seen 2 ... Which were brought by my clients to India for shikar . It is an excellent calibre for our 300 pound Bengal Bush Boars , and our Sun Bears ( The smallest of the Indian Bears ) .

 

[WebleyGreene455]

Oh definitely , Webley . The gaur is the most difficult to dispatch ... among India's " Dangerous 6 " . This is because the gaur has EXTREMELY thick muscles . Think of them as ... the body builders among the bovines , or the Arnold Schwarzenegger of wild cattle . They are also extremely unpredictable ... in terms of behavior .
If a gaur comes across a human being , it will either ( by way of COMPLETE randomness ) :
> Flee from the human beings .
> Ignore the human beings
> Attack the human beings , ON THE SPOT
> Pretend as if it is moving away ... only to circle around the human beings , flank them from behind and THEN attack them .
Even though I have no experience with African Cape buffalo , my reading seems to indicate that most African Cape buffalo average about 1300 pounds in weight .
By comparison ... A fully grown bull gaur can weigh anywhere from 2000 pounds to 3000 pounds .
Here are 2 of the 15 bull gaurs ... which I have personally dispatched , to put matters in to perspective .
View attachment 347435 View attachment 347436
Here is 1 dispatched by a client of mine .
View attachment 347437

They seem closer to American bison in their weight, then. Our "big shaggies" typically range up to some 2700-odd pounds at maturity, for males. I'm unsure of their overall temperament, though. People have been attacked by them, of course, possibly unprovoked in some cases, but I've no idea if they display the same degree of aggression. Certainly the yearly number of bison attacks in the US is lower than that of yearly Cape Buffalo attacks, though.

 

[Brian Rothhammer]

I don't know what stood out to me about about this caliber, but its been a toss-up between that and the .404 in my mind and it came down to the 10.75 strictly because people don't hunt with it anymore. Horrible reasoning I know but I blame the books for that one. Realistically speaking, this gun wouldn't necessarily be a buffalo gun until down the line and even then I'd prefer something bigger.

From _Dangerous Game Rifles_ by Terry Wieland:
In Germany at this time, several gunmakers developed rimless cartridges for Mauser and Mannlicher rifles. The most popular in Africa was the 10.75X68 Mauser (bullet diameter .424"), which was introduced in the 1920s. It fired a 347-grain bullet at 2,200fps. There was nothing wrong with the cartridge, but bullet performance was poor. Bullets tended to break up and not penetrate, and their users tended to not come home. In a modern rifle with good bullets, this is an excellent cartridge in the .375 H&H class.

Excerpts from a reply posted to a query on another 'site regarding a Haenel 10.75X68:
... The 10.75x63 and later by 68 was developed primarily for African use. Custom Mausers were much less expensive than the British double-rifles and became popular with the Boers and other settlers of European descent who couldn't afford a double...
...The 10.75x68mm cartridge that your rifle is chambered for developed a very bad reputation in Africa due to a combination of poor sectional density compounded by poorly constructed bullets. The combination of the two resulted in very poor penetration.

With the premium bullets available today, I'm sure that it would prove to be adequate for all plainsgame and Lion, however the typical bullet weight per the original load is 347 grain in either softs or solids. Here is a quick cross reference based on the data published by Woodleigh bullets on their website. They provide modern, high-quality bullets for the old obsolete cartridges. This data compares several cartridges deemed as dependable in the large-medium bore category. Your bullet diameter is .423.

Cartridge ~ Bullet Weight ~ Sectional Density ~ Ballistic Coefficient

10.75X68mm ~ 347 Gr. .~ 277 ~ .290

.416 Rigby ~ 410 Gr. ~ .338 ~ .307

450/400 NE ~ 400 Gr. ~ .338 ~ .307

.404 Jeffery ~ 400 Gr. ~ .321 ~ .335



Cartridges: http://www.cartridgecollector.net/1075-x-68-mauser

 

[Brian Rothhammer]

Beautiful pieces of art , Mr. Rothhammer . I myself have only ever seen 2 ... Which were brought by my clients to India for shikar . It is an excellent calibre for our 300 pound Bengal Bush Boars , and our Sun Bears ( The smallest of the Indian Bears ) .

The 10.75 pictured is not mine, alas, but I'll always have Grand dad's M1910 Takedown Model (9.5X57).

My mother (born at Colombo, Ceylon) was given a sun bear cub by a local Rajah (or some title, I'd have to look at Grandma's old notes) when she was a child in Singapore. Her parents graciously accepted it but before much time had passed they turned it over to noted animal collector Frank Buck. At any mention of Buck's name or signature phrase, "Bring 'em back alive" she would say, "He took my bear!"

 

[One Day...]

Looking at my Kar98k's mag box, I would think there was sufficient room for the 1.6mm difference in OAL between 8mm and 9.3x62mm, compared to the 7+mm difference in OAL between the .458 Win and .458 Lott. But I expect some slight modification to the feed rails might be needed for a conversion between the two German calibres.

Yes indeed.

Different lengths also mean different shoulders location and characteristics in bottleneck cartridge designs.

In this case:

• The 8x57 case head measures 11.95mm, therefore: 0.866 x 11.95 = 10.35 +11.95 = 22.3mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 22.4mm at the case head.
• The 8x57 case measures 10.95mm at the shoulder, therefore: 0.866 x 10.95 = 9.48 + 10.95 = 20.4mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 20.5mm at the shoulder.

• The 9.3x62 case head measures 12.1mm across the rim, therefore: 0.866 x 12.1 = 10.48 + 12.1 = 22.6mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 22.7mm at the case head.
  
• The 9.3x62 case measures 11.45mm at the shoulder, therefore: 0.866 x 11.45 = 9.92 + 11.45 = 21.4mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 21.5mm at the shoulder.

• The 10.75x68 case head measures 12.6mm across the rim, therefore: 0.866 x 12.6 = 10.9 + 12.6 = 23.5mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 23.6mm at the case head.
  
• The 10.75x68 case measures 12.2mm at the shoulder, therefore: 0.866 x 12.2 = 10.6 + 11.45 = 22.8mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 22.9mm at the shoulder.

In consequence:

• A magazine box for the 8x57 must taper from 22.4mm to 20.5mm, and the rail relief must be located at the proper location.
• A magazine box for the 9.3x62 must taper from 22.7mm to 21.5mm, and the rail relief must be located at the proper location.
• A magazine box for the 10.75x68 must taper from 23.6mm to 22.9mm, and the rail relief must be located at the proper location.

While I do not think that a difference between 8x57 and 9.3x62 of 0.3mm in magazine width at the head would make a huge difference (although it would have bothered Paul Mauser), a difference of 1mm in magazine width at the shoulder begins to be meaningful, and a difference of 5.6mm in the position of the shoulder (46.2mm from head for 8x57 and 51,8mm from head for 9.3x62) is meaningful for the cut of the relief in the rails.

So yes, the difference of 1.6mm in the two cartridges overall lengths is likely meaningless, and they fit in the same action length, but they ideally need two different magazines and rails geometry. Granted, the differences are small in this scenario, and the 9.3x62 will likely work in an untouched 8x57 action, but modifying the magazine and rails per the above calculations is what makes the difference between a rustic re-barrel job, and the refined conversion job that translates into 100% reliable and butter smooth feeding.

When it comes to moving from 8x57 to 10.75x68, the difference of 1.2mm in magazine width at the head and 2.4mm at the shoulder will make a significant difference and a difference of 7.2mm in the position of the shoulder (46.2mm from head for 8x57 and 53,4mm from head for 9.3x62) will be important for the cut of the relief in the rails.

This is why converting the standard M98 to .416 Rigby was such a delicate process, because in addition to having to cut 13mm (!?!?!) off the feeding ramp (and lower lug recoil shoulder), the magazine and rails had to be widened 5.5mm (!?!?!?), not to mention opening the bolt face to its almost full diameter...

 

[Panther Shooter]

I do not have any personal experience with the 10.75x68 millimeter Mauser , because I only became a passionate Shikari in 1973 . However , I do know of a ( recently deceased ) Anglo Indian former Shikari in Bangalore ( by the name of Don Anderson ) who shot one Spotted Leopard with a 10.75x68 mm Mauser .

@Major Khan Sir knew Don personally , so he can comment upon this with far more knowledge and accuracy than I .

 

[Brian Rothhammer]

Hey guys! I am looking into putting together a rifle in the old 10.75x68 Mauser cartridge and am wondering what action I would need to be looking for to fit this round.

A previous thread on the fine and reputable 'site, AfricaHunting regarding 10.75X68 builds: https://www.africahunting.com/threads/mauser-98-in-10-75x68.37193/

 

[WebleyGreene455]

Yes indeed.

Different lengths also mean different shoulders location and characteristics in bottleneck cartridge designs.

In this case:

• The 8x57 case head measures 11.95mm, therefore: 0.866 x 11.95 = 10.35 +11.95 = 22.3mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 22.4mm at the case head.
• The 8x57 case measures 10.95mm at the shoulder, therefore: 0.866 x 10.95 = 9.48 + 10.95 = 20.4mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 20.5mm at the shoulder.

• The 9.3x62 case head measures 12.1mm across the rim, therefore: 0.866 x 12.1 = 10.48 + 12.1 = 22.6mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 22.7mm at the case head.
  
• The 9.3x62 case measures 11.45mm at the shoulder, therefore: 0.866 x 11.45 = 9.92 + 11.45 = 21.4mm. Add 0.1 mm for tolerances in cartridge dimensions and field damage. The magazine box must be 21.5mm at the shoulder.

In consequence:

• A magazine box for the 8x57 must taper from 22.4mm to 20.5mm, and the rail relief must be located at the proper location.
• A magazine box for the 9.3x62 must taper from 22.7mm to 21.5mm, and the rail relief must be located at the proper location.

While I do not think that a difference of 0.3mm in magazine width at the head would make a huge difference (although it would have bothered Paul Mauser), a difference of 1mm in magazine width at the shoulder begins to be meaningful, and a difference of 5.6mm in the position of the shoulder (46.2mm from head for 8x57 and 51,8mm from head for 9.3x62) is meaningful for the cut of the relief in the rails.

So yes, the difference of 1.6mm in the two cartridges overall lengths is likely meaningless, and they fit in the same action length, but they ideally need two different magazines and rails geometry. Granted, the differences are small in this scenario, and the 9.3x62 will likely work in an untouched 8x57 action, but modifying the magazine and rails per the above calculations is what makes the difference between a rustic re-barrel job, and the refined conversion job that translates into 100% reliable and butter smooth feeding.

I see. Since I've been considering a conversion from 8mm to 9.3x62mm (not on my Kar98k; that's just gonna get a repro PE scope and a side rail mount to make an early-war sniper mockup for possibly-DAK reenacting and range fun), I'm sure I could find someone who could easily handle the rail cut along with the rebore of the existing barrel, if I end up going that route.

 

[Major Khan]

I do not have any personal experience with the 10.75x68 millimeter Mauser , because I only became a passionate Shikari in 1973 . However , I do know of a ( recently deceased ) Anglo Indian former Shikari in Bangalore ( by the name of Don Anderson ) who shot one Spotted Leopard with a 10.75x68 mm Mauser .
View attachment 347454
@Major Khan Sir knew Don personally , so he can comment upon this with far more knowledge and accuracy than I .

I remember this clown all too well , Panther Shooter . That is Kenneth Anderson's son ... Donald Anderson .
Yes , Don DID dispatch 1 female village panther with his .423 Mauser calibre Mauser 98 Oberndorf bolt rifle . The panther weighed 136 pounds . Don used old ( pre 1947 ) ICI Kynoch 347 grain soft point cartridges to dispatch the brute .
But look what it cost him . He lost 2 men during this shikar . Don had to shoot it 5 times , and the panther still survived long enough to tear out the throat of 1 of Don's coolies and then fatally maul Don's tracker . The poor tracker battled with death for 3 days ... before dying from the infections caused by the wounds which the panther had inflicted .

Of course , Don being Don ... Later attempted to milk his way to fame among the Indian anti hunting crowd , by saying ( in his later years ) that the death of his 2 men was a message from God for him to stop hunting . What a joke .

 

[Panther Shooter]

I remember this clown all too well , Panther Shooter . That is Kenneth Anderson's son ... Donald Anderson .
Yes , Don DID dispatch 1 female village panther with his .423 Mauser calibre Mauser 98 Oberndorf bolt rifle . The panther weighed 136 pounds . Don used old ( pre 1947 ) ICI Kynoch 347 grain soft point cartridges to dispatch the brute .
But look what it cost him . He lost 2 men during this shikar . Don had to shoot it 5 times , and the panther still survived long enough to tear out the throat of 1 of Don's coolies and then fatally maul Don's tracker . The poor tracker battled with death for 3 days ... before dying from the infections caused by the wounds which the panther had inflicted .

Of course , Don being Don ... Later attempted to milk his way to fame among the Indian anti hunting crowd , by saying ( in his later years ) that the death of his 2 men was a message from God for him to stop hunting . What a joke .

Major Khan Sir
Like father , like son .

 

[Brian Rothhammer]

Original 1925 Maus action:

Text from nine year old post to another 'site:
I am offered to buy a Mauser 98 mechanism with a octagon barrel. Its octagon halfpart and then the rest is round. It looks alright inside. The man who is selling it is a good technician and has his own gun store, in the past he worked at Kongsberg, Norway. It will be polished and blued. The calibre is 10,75x68. Its made september 1925. The price is $920. What about the calibre? The price? Anything? Grateful for advice. //Staffan

Mouser:

 

[Red Leg]

Major Khan Sir
Like father , like son .

This is why it is so wonderful having you gentlemen part of our group. It is also a reminder that when even a small leopard decides to turn on his tormentors he can be extraordinarily dangerous.