Actually, the reason most retailers will not export are due to The International Traffic in Arms Regulations (ITAR) regulations. A commercial entity needs an export license to ship any gun stuff to RSA, and the receiver must be approved before the shipment. Being in the gun stock business, I can tell you customers' shipments do get confiscated, but generally its not a foreign tourist shipping his stock back home that loses their shipment, its usually someone shipping a large load of goodies, or when they put "auto parts" on the customs form when its really a trigger assembly or some such. Best to follow the rules these days.
The federal laws are very detailed and specific:
US State Department - Policy - Directorate of Defense Trade Controls
That been said, i know Safari & Outdoors in the Lynnwood Bridge Shopping Centre, Pretoria can make arrangements to get U.S. made supplies into RSA because they carry our stocks. They have a stateside rep with the required permits to ship US goods to for forwarding, however I do not know their policies as far as customers' own goods are concerned.