Which (see below) got me to thinking about those Mausers...
A Model 1895 (Mexican Army)
In the Anglo-Boer War of 1899-1902, Boer Commandos - armed with Model 1893/1895 Mausers - proved to be an exceedingly tough match for the Brits. One of the constant themes of the conflict was the accurate, long-range fire the Boers rained down on their adversaries. As the Boers would put it, "Vertroue in God en die Mauser" --"Faith in God and the Mauser."
This is interesting. "The Model 95 (7x57) was adopted by Chile, Mexico, Uruguay, Persia, China, the Transvaal and the Orange Free State. In fact, some of the Chilean Model 95s carry the code "O.V.S.", standing for the "'Orange Free State." Reportedly, because of the success of the British blockades, these rifles never reached South African shores, were returned to the factory where the Chilean crest was applied to the receiver ring, and sold to Chile as part of the contract." (From Guns Magazine, August 2007)
And this article from Wikipedia discusses the 7x57 ammunition. Here's an excerpt:
The qualities of the 7x57mm as a military round were shown in the Spanish-American War and the Second Boer War in South Africa. Teddy Roosevelt and the Rough Riders took very heavy casualties attacking an inferior force armed with 7 mm Model 93 Mauser rifles. Likewise, British soldiers fighting in South Africa were obliged to re-evaluate rifle and ammunition design and tactics after facing Boer sharpshooters and snipers armed with Model 1895 Mauser rifles firing 7x57mm rounds with withering effectiveness, easily outranging the .303 British cartridge as regards accurate long-range fire. The .303 cartridge at that time was still using cordite propellant, in contrast to the Mauser's higher-performance ballistite type smokeless powder.
I found this photo of a slightly newer Mauser rechambered for a NATO 7.62mm.