The following information on the Argentine Mauser 1891 Model comes from Chapter 17 of Mauser Rifles and Pistols by W. H. B. Smith. Mauser Rifles and Pistols is also available to purchase in print.
In 1891 Argentina adopted a slightly modified version of the Turkish rifle. It was improved with a strengthened bolt.
The caliber of this rifle was also 7.65mm or .301 inch. The length of the rifle was 48.5 inches, and the weight without bayonet about 8.5 pounds. The bayonet adds 1 pound of weight.
The arm could be single loaded or loaded with the Mauser clip of 5-cartridges in standard fashion. The cartridges were retained in the standard magazine in single line.
The cartridge was 3.07 inches long, and weighed about 1 ounce. The bullet was 1.2 inches long, lead with a cupro-nickel jacket and weighed about .5 ounce. The powder charge was about 40.9 grains of smokeless originally giving a muzzle velocity of about 2066 feet per second with a chamber pressure of about 39,000 pounds to the square inch. Maximum bullet diameter .311 inch.
The rifling was 4-grooves to the right, one turn in 9.8 inches. Sights were graduated to 2000 meters.
Slight modifications of this rifle and of the ballistics of the cartridge were made, but essentially they remained the same, though in recent years modifications of the German Kar. 98 have also been used.
Later Argentine Mauser Patterns
In 1895 Argentina purchased a quantity of rifles from Germany based on the Spanish 1893 Mauser design. Later rifles based on the Gewehr 98 pattern were purchased from both Germany and Spain. Caliber before World War I was uniformly 7.65mm Mauser. Some in 7.92mm caliber have since been delivered.
From 1924 on the Belgian F.N. factory supplied Mauser System rifles to Argentina and other nations. These were all made to the general specifications of the official German Kar. 98 except for such modifications as were required by the difference in caliber. A reading of the chapter on the later German types will effectively cover these later Argentine Mausers.