I never worry too much about published factory ballistics because they are all shot through long pressure barrels. No matter who is the manufacturer. I buy a box of the factory loads that I want to duplicate, and shoot them over the chronograph to check accuracy and velocity. I will also measure the CHE (case head expansion) for another point of comparison. After some testing, I was able to duplicate the velocities obtained with 154 and 175 gr. factory ammunition in the 7mm Weatherby with IMR-7828. I got close to the 180 gr. velocities in the .300 Wby. with that same powder, but did not go any further since I was shooting 200 Grand Slams in the .300. One thing that is overlooked in Weatherby rifles is the safety and trigger mechanism. The triggers are easy to adjust and compare to the better custom triggers. I took an unplanned header off of a mountain a few years back, and had my 7mm Weatherby loaded with the safety on, since I was tracking a wounded deer. The safety did exactly what it was designed to do, which is quite a bit better than some of Weatherby's larger competitor's models. Both me and the rifle recovered from that experience with no serious lasting effects. As a bonus, I can sense oncoming weather changes with my left wrist and knee, and I got a free ride in a Huey courtesy of a Navy Seals rescue team.