9,3x62. Classic, made for Africa, got 17 years on the Whelen.
The 35 Whelen is basiclally a poor bastardization of a classic European cartridge.
Most likely didn't want to pay royalties... since there where rife with Mauser rifles chambered in 9,3x62 to be had.
And 9,3x62 ammunition could be bought anywhere on the African continent at the time.
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