It is my understanding that the airlines permit a max of 11 lbs of ammunition in total to be transported. It appears from my reading of RSA's regulations you are restricted to 200 rounds total irrespective of caliber. In no case can you exceed the international airlines rule of 11 lbs for transport by air. That would mean 200 17Mach2's
which would be well under the 11 lb rule but you could not take 200 470's because that would be in excess of the 11 lbs. You are talking about 2 regulations here one concerning airlines and one concerning import into RSA.