I never shot them. But being a buffalo bullet you would want to start them out with a low powder charge and then work up to something your rifle likes and you can handle. 70 grains would be a good starting load. With that kind of weight, if your hunting deer, that is plenty. What rifle and barrel twist are we talking about here? Also since they have a flat base, you might consider a wad, bore button, or even 20 grains of cornmeal between the powder and the bullet to help seal it and protect the base of the conical.