Last deer season I shot a doe about 250yds with a 140 Amax out of my 264 behind 66 grns of retumbo. As soon as I shot her she did a complete backflip and never moved again. There was a litte entrance hole the size of a pencil and no exit hole. When I gutted her the heart and lungs were nothing but jello I was pretty impressed. With that said I think I am gonna try the 140 sst because I would like a litte bigger entrance hole in case a deer would run off after you hit it I think it would be easier to track.