Unique Cartridge

Hello, I am a new member. Have been to Africa three times and use a Schoenauer I had NECG put a S&B 1.5to6 power in claw mounts... 30-06 for plains game.
Question for the site, however, is my double... It is a Robert Schuler. The Cartridge is a .375 flanged that has been blown out to accept .423 diameter 404 Jeffery A-Square deadtough and mono solid 400gn bullets. It is marked 10.3X70R on the bbl flats. I had Jameson make up a few hundred cases with the proper headstamp. I am running at 2175fps and downed a buffalo and tuskless in Zimbabwe with it.
Wondering if anyone here has heard of this cartridge before. It obviously was a wildcat back in the late 20's when it was made??? Thanks, Bob

Only thing I could find on it (even close to it) was the 10.3x60R which was the Swiss version of the 450/400. Ammo was being manufactured from 1919 all the way up to 1991. Sound like you have a very unique, if not a one of a kind, there is nothing on the net about it or in any of my books. My guess would be like the 45-70, someone wanted a 45-90 so they built one. The original owner of your rifle probably did the same.

Originally Posted by 35bore

Only thing I could find on it (even close to it) was the 10.3x60R which was the Swiss version of the 450/400. Ammo was being manufactured from 1919 all the way up to 1991. Sound like you have a very unique, if not a one of a kind, there is nothing on the net about it or in any of my books. My guess would be like the 45-70, someone wanted a 45-90 so they built one. The original owner of your rifle probably did the same.

BTW. It has the same balistics as the .404 Jeffery. It hits quite hard.

there is also 10.3x65r baezinger which was used for target shooting in europe. apparently it has the same power as a .44 mag fired in a rifle, so no where near your one. it a lot less powerfull than the 10.3x60r mentioned above which had just over 3,000ft/lbs at the muzzle. i wonder who thought it up and went to the trouble with a double back then?

Welcome to the forum, Bob, it seems that you have quite a rare cartridge !

got any photos of your double rifle bob?

Attachment 13500
If I did it right there is a picture of my rifle on the right and my PH's 500NE Sabatti on the left. (I gave it to him in 2010, Hilton Nichols).
It was made in the 20's. From what figure, Schuler wanted a 404 Jeffrey (.423 caliber) but needed a rim (flange) for the double rifle so they used the .375 flanged case and blew it out to accept the bigger bullet. By the book, it has 4150 ft ME. Remember, the 10.3 is the bore size. It is about 10.7 groove size. I love the results with the A-Square dead tough and mono-solid. I use 64 grains of IMR 3031.

Welcome to AH gatlingman.
Where do you guys keep finding these odd/unique calibers.
There must be a lot of creative gunsmiths out there.
I just keep learning.

Originally Posted by gatlingman

Attachment 13500
If I did it right there is a picture of my rifle on the right and my PH's 500NE Sabatti on the left. (I gave it to him in 2010, Hilton Nichols).
It was made in the 20's. From what figure, Schuler wanted a 404 Jeffrey (.423 caliber) but needed a rim (flange) for the double rifle so they used the .375 flanged case and blew it out to accept the bigger bullet. By the book, it has 4150 ft ME. Remember, the 10.3 is the bore size. It is about 10.7 groove size. I love the results with the A-Square dead tough and mono-solid. I use 64 grains of IMR 3031.

i was wondering about using .404 bullets in a 10.3mm when the metric designation for the .404 jeff is 10.75x73mm. is that the double in the photo of your buff?

The piture of the double with my buff is the Sabatti that I ended up giving to my PH. (It hurt me real bad from the recoil... Not as tough as I thought.) It is a 500NE. My Schuler is seen by clicking on the previous thread entry marked "attachment 13500".
A 9.3x72R is designated as an 8.8 on the bbl flats on most drillings that shoot that cartridge. The Europeans measured how big a steel roller bearing ball would fit down the barrel. We slug the same bbl and measure the biggest diameter of the slug... them 8.8/ us 9.3 ,same barrel.
Schuller measured bore size of 10.3 while the caliber (slug size) is 10.75. I would have had the cases marked 10.75X70R when I had them custom made but that would not have matched the barrel flats that are marked 10.3X70R. My bbl slugs at .421.
I hope this makes sense, my head is spinning so I better stop... :-)

BTW... I have the HIGHEST respect for the doubles that Sabatti is selling through Cabella's. They are VERY well made and are a great buy for the price.

Here is a photo of Gatlingman's rifle. I have a better one but have not uploaded it to be able to post. the Schuller is the gun on the right. That's me on the right and Gatlingman on the left. I can vouch for this guns effectiveness and accuracy. I will try to upload a closeup photo later.