When I first start loading with a 300 wby I load 82 grains of H4831, cci250 primer and seat the 180 just short enough so it will feed through the mk 5 action. This is a generic accuracy load good in any 300 wby with freebore. I always try this first to see if it is a shooter. I have never seen a mk 5 that did not shoot this load well. Velocity is right at 3200 fps in a 26" barrel. Some newer powders will get more velocity. But this is a shooter to try in any 300 wby.