303

There is no doubt a .303 or even a .30/30 can be used to kill a water buffalo.Thousands of buffalos have been killed with .303's and .44/40's in the old days. But most of these were shot from horseback or from the back of a Landrover or Landcruiser. A horse can gallop away faster and a Landrover is a harder target for a charging buff than a human on foot. Undoubtably a lot of buffalo also were wounded and escaped. These guys were commercial hide and meat shooters so different rules applied when buffalo were very plentiful.

Nowadays a lot of Aussie hunters still use .30-06s, .300s etc. A lot of them are still shooting them from backs of Landcruisers. Most guides advise or even insist on a .375 H&H Mag powered cartridge.