dufus, I too have a weatherby mark V, this one is chambered in 30-378. good call on the lower velocity - pressure keeping barrel up life. I don't know if I can shoot that big cartage subsonic, might be the next thing for me to try. Even if it is supersonic but not eating the thought out it might have the advantage of trigger time. Got to say, low velocity 30-378 completely defeats the purpose of owning such a rifle, but what the heck.