I don't know what kind of ammunition is most easily obtained in remote jungles and deserts but interestingly enough, some adventure movies actually filmed overseas in the 1930s often as not show Colt Single Action Army revolvers being used. Rifles were invariably Winchesters but not necessarily carbines. One silent movie, The Lost World (the 1925 version, not the one with Jill St. John), I have shows a Luger being carried, though you can't tell what caliber it is. Another movie from 1940 in which a Luger appeared (uncredited) was clearly a .30 caliber, because you saw the empty shell (or at least the shell was a .30 caliber Luger, the bottleneck being obvious).
Actually, I doubt very much was available in the way of handgun ammunition in very many foreign places during the 1930s, but it's interesting to think about.
One biographical book I have, "I married adventure," was about Martin and Osa Johnson, who autographed my copy. The flew around Africa and Southeast Asia and the Pacific making travel/nature films. At one point in her book she lists the guns they brought along and said she was embarassed at how long the list was. But I believe there was only one handgun.
Shoot low, sheriff. They're riding Shetlands!
Underneath the starry flag, civilize 'em with a Krag,
and return us to our own beloved homes!
Buy War Bonds.