Hello Igorrock;

Glad you asked. Not really...I'll fill you in on the 9.3x64 Newton now:

The case does look similar to the 9.3x64 Brenneke. But the 9.3x64 Newton case has more volume, I have a 9.3x64 Brenneke case & its case volume I carefully measured of this RWS case as 84.0 gr. water. The 9.3 Newton has 89 gr. water. However, the larger volume & more powder at the top end loading makes a good difference in velocity.

Here's how I made the 9.3x64 Newton. Its simply a .35 Newton case necked up to 9.3 caliber. The Newton cases are very good, a modern type case design with a big body, yet standard size length (.30-06 length).
However, even though .35 Newton cases are being made...they are too expensive! A better way is to just buy .375 Ruger brass, shorten the brass to 2.5 inches long & size it in the 9.3x64 Newton die.
You can also buy .375 Ruger "basic" brass that has no caliber headstamp, have it headstamped 9.3x 64 Newton, then size it.
Now...I have a .35 Newton chamber reamer...so my gunsmith used that on a 9.3 barrel, then a 9.3 neck reamer to make it the 9.3. I fired 3 cartridges, send the fired cartridges to Hornady and they made the custom 9.3x64 Newton dies for it. Since then, all I do is use .375 Ruger brass, shortened & sized
in the custom dies.
I corresponded with Harold Wolf as he made a 9.3x70 mag. rifle, and giving him my 9.3x64 Newton
ballistics, he said it was more than what he got from his 9.3x70 mag. and warned me about too high
pressures...but my pressure is OK.
If you put the 9.3x64 Brenneke next to the 9.3x64 Newton, you will notice that the Newton case has
a larger base, and shoulder diameter, and the shoulder angle on both cases look the same. The Newton
case neck is very slightly longer...but not much. Case lengths about the same. Its a better looking
case than the 9.3x64 Brenneke.I'm not sure if you know of Charles Newton, but he was the greatest
American case designer. I made the 9.3x64 Newton, a .416 Newton & a .450 (.458) Newton based on the
same parent Newton case...and they are all superior cartridges.
Best Regards,
Tom from Wyoming