Well, in my experience with other pistols and what you're describing I'd want to say the magazine springs are too weak and may be the issue. Especially with all this nose diving going on. I know your triple k magazines are new but I'd try to find a stiffer spring that will work with the magazine.
I don't know if this will work but I'd try swapping out the jetfire or protec mag spring with the triple K magazine spring and give it a whirl.
Magazines and their springs are crucial elements of semi-autos and if they are not made to spec with quality materials aftermarket magazines can indeed give you headaches, been there done that.