I have used a variety of bullets to take deer but one that stands out was the 100gn Swift Scirocco in my .257 Roberts. I took a good fallow buck last year at 20 metres at a slight forward angle. The bullet entered just in front of the left shoulder and lodged under the skin about 6-7 inches behind his right foreleg. It weighed 79.0 gr (79% weight retention) and formed a nice mushroom. Considering the close range and velocity (>3100fps) I thought it held up very well. The buck dropped on the spot. It's only an example of one but I was quite impressed.