Wait a minute there. Those tests don't say nearly as much as some here contend. It's like comparing apples and oranges. The joint pin on the 21 is further from the breech face than any of the other guns. While I don't know the various wall thickness of the guns compared I suspect the 21 is no light weight in that department and may even be the thickest of the lot. But the most critical thing has to be the distance from joint pin to breach face. This factor will dwarf all others when assessing how much strain an action will endure before failure. Quality of steel is way down the list.
nial
There are too many variables to categorically say any one thing is what makes one gun superior in strength to another. So, I think you hit the nail on the head: apples to oranges. But you can determine that one gun is stronger than another thru testing. In the end, that's useful to some people. If one company uses steel that is 20% stronger than the next guy, but does not utilize it efficiently in his design, it may result in a lightweight but understrength product or a product that is heavier than desired and stronger than necessary for the job.
I'm in the airplane biz. We can make stronger airplanes, but they become less efficient. Somewhere there is a range of balance of the requirements. Within this range, there is an optimum design for the constraints at hand.
