My view on this has been the same for many years. The MK5 action has been around since the 50's and from the outset has always been assigned the task of handling pretty much the most powerful cartridges available in any given bore size.

It's just a stretch for me to take an action that's been around that long that's spent that much time shooting bigger-than-average cartridges and assume it's not acquitted itself beyond any other reasonable expectation for something made by man and subject to failure. One almost wonders if the fact it's such a big deal when one seemingly does fail (and it's funny how often user error still seems to usually be in play) if it isn't almost a complement.

I've got an MK5 .340 and am not the least bit afraid of it. I don't know how much "better" it is than other actions but I've never seen any real world/non-anecdotal evidence to suggest it's worse.

If there's one thing I've become certain of it's that there's too much certainty in the world.