I haven't taken a whitetail with them, but both myself and my friend have both taken some feral hogs out past 300 with them and they dropped like you pulled their plug's. We're using them in factory rifles, and getting 1" groups at 200ys. The load is 55grs of Ramshot Hunter, and Win-WLR primers, and Win cases. I am getting just over 3K fps from my 22" barrel. This load is pushing the top endf for my rifle so I would definatley start low and work up to it. This load also hits perfectly with the Burris B-Plex I have on it. They sure make a slap when they hit as well, which I am sure has a lot to do with the hide on those porkers. The last one I shot was a boar around 200#. He was ranged at 328yds trotting across an open pasture, the hit was just behind the left shoulder and came out just in front of the right. He did a header and that was that.
They might be a little much on a deer up close but they sure haven't let us down on the hogs.
Good luck
