According to Jon Speed's book, there were 2 pre-World War I Mauser distributors in South America:

Federico Maurer (Santiago)
Bellingrodt & Meyer (Rio de Janiero)

By 1938, the network had expanded to include Lima, Buenos Aires, Guayaquil, Sao Paolo, La Paz, and Montevideo among others.

There must have been a fair number of Mauser sporters shipped to these dealers, as well as all those Winchester 54's and 70's in 7.65 mm and 9x57 that one is always hearing about. I would think that, unlike guns shipped to Germany and elsewhere in Continental Europe, many of these guns must have survived.

Does anyone have any idea about the numbers of rifles shipped to S. America and how to go about looking for them now? I have searched in vain for auction houses in South America and haven't had much more luck in finding dealers.

To me it is a fascinating subject.