1.) Two cartridge families: 240-257-7mm-300-340, and, the five 378-based carts. Do they use the same Mark V action or is there a difference in actions besides the bolt face diameter ? Is there a "short" and a "long" action version ? 2.) What is the diameter of the action(s), or, the max diameter of the barrel at the big end ? I know the Rems are 1.200~1.250. Trying to get an idea how much bigger/stronger they are over the Rems. Going to start a Weatherby project and need to know what is what.