I own a MKV, left to me by my uncle, a gunsmith. He educated me on the features of the MKV vs all the rest.
The two opposing locking lugs of most conventional rifles require a lot of material to be removed from the barrel to accommodate the large locking lugs. The bolt is smaller in diameter than the MKV bolt.
The MKV bolt is the same diameter of the 9 locking lugs, arranged in three rows of three.
The MKV action is widely accepted to be the strongest action available. It has proof tested conditions that destroyed every other action tested. The test was, place a 180 gr bullet a few inches into a 300 WBY barrel, from the breech, load an other 180gr hot load, and shoot. In this test, both bullets were swaged and exited the barrel. The action was damaged, it had swollen by .003", and required a gunsmith to open. Every other rifle tested, all of them you or I could name, split like ruptured banana in front of the receiver for about 10-12". This reduced the forend of the stock into schrapnel and would have maimed if not killed the shooter. The receivers and actions were ruined and most bolts failed in this test.
Roy Weatherby is supposed to have gotten the idea for the bolt from artillery receiver blocks. These blocks feature an interrupted screw design that required less travel to engage and to disengage.
The design was praised to me by my gunsmith uncle, and he left me a 340WBY MKV Deluxe, circa 1972. So, I may not be very objective about this action. God Bless you Uncle Bill!
Having the receiver portion of the barrel and the bolt, the same diameter, while heavier, has no less contact, than dual opposed locking lugs. I believe that it has been verified that it is the strongest available.
