Hi lancaster...

Je,je...!

Joke apart, the 7,65x53 Belgian Mauser cartridge (the identification, mainly in the USA, as the Argentine Mauser is due, I think to the flood of "our" 1891 and 1909 Mausers....imported there in the '60 and '70), it is VERY similar to the .308 Win / 7,62x51 NATO, and the 7,5x54 French as well. But only 50 years or so before the French one...
The lenght of the cartridge, the short neck, and the ballistics of the 7,65x53 Mauser, with the powders of that era, makes them a wonderful military cartridge, even with today standars!!
It is said it was the favorite of the Mauser itself...
Here, in Argentina, it is still used for hunting, because our fantastic Mausers relatively available.
It is common to use .30-06 cases converted, very easy, to the 7,65x53. Bullets are available in Sierra .311", although not exactly the bore size of the 7,65, and Hornady .312" are the most common.

Best!

PH