Kalashnikov could not construct anything because he had only 7 classes of school behind him.
Well, of course, Spagin with his three classes of church-parish school could not think of anything like that, Degtyarev and Tokarev too, suddenly, universities did not end, but about John Browning or John Garand and nothing to say.
Stoner also, by the way, had no formal engineering education - from school to factory, from there to the army, from there again to the factory - and forward.
Of course the worst thing is myself!!! Hugo Schmeisser received no formal education other than high school. at all. I mean entirely.

But the current networked military with a higher humanitarian education in history and an iPhone instead of a brain very well know who and what can create.