You don't have to be a "qualified gunsmith" to work on your guns.
Depends on the definition of the word, 'work'..
However, you do need to have a full understanding of the mechanisms you are working on.
Yep, which is what the definition of the word 'amateur' lacks.. The word 'full', is operative there..
You do need to have correct tools such as ones a qualified machinist may have.
Which the majority of amateurs lack.
Oh well, what do us amateurs know?
Sometimes, just enough to be dangerous..
As a parallel example: a professor in an Ag law course I took reminded us often, of this very true sentence: "A little knowledge of the law is a dangerous thing".
Ya might wanna study that one a little, there, Chiefy boy...
We got a few amateurs near me too.. They help pay for my monthly bills.. God love 'em...