You might do well to seek an understanding of the networks there. The US gun market works totally different to other countries. I suggest you may find that there are a substantial number of guys in South America who are into fine gear, but may be catered for by dealers with obscure shopfronts and 'by appointment' opening times.

Start by asking the members here and other major forums who have South American locations where THEY would look.

If you are able, perhaps you could also help people out with parts or books that are easy to get in the US but hard to find in their countries. Network building can be a two-way street.