Exactly David! I wouldn't agree that you can learn or master any task by perseverance. Accurately setting up a bolt is an art learned after being taught as apprentices after being taught the reasons for each of the 6 associated functions. But mastered by being shown by someone who's done it a zillion times and knows exactly what to look for. Or what about bolt heads, or Bren locking shoulders - or L1A1 locking shoulders........ or barrel nuts......., who glibly just think that it's a straightforward swop. Nope......., most people didn't have the remotest idea that while there might be numbers on them but in real life, they're pretty well meaningless.