If it were me I would sell your 7mm RM that you don't quite like and sell the 375 Ultra Mag too. Keep your 338 since you love the round and get the 375 Ruger. I looked hard at the 375 Ruger before commiting to buy one, had grizzly mostly in mind but wanted it to be versatile too. Looking at ballistic tables it will work well with a bullet like the 260 Accubond to take a 400 yard + shot on a moose if I am up to the task. Look forward to working with the round in the months ahead.
