Had the same situation a while back here. We were driving in the bush when we came upon some aggresive meerkats (ground squirrel). Fortunately we saw them first, and I had some time to choose between my 375 and my 303, both fitted with iron sights. Because it was a longish shot at about 90 yards and the fact that the 303 was loaded with 180gr bullets I decided on it. Well, the first meerkat fell with a proper hart/lung shot. The rest charged us and we had to make a hasty retreat. We just had the time to get into the vehicle and sped off. HA-HA.