I'm digging through paratrooper right now and upon getting to mortars it claims you should have gone through MG training but... I must have missed it? Rifles, CC, Morale, Concealment,... what am I missing?
Well, the text says nothing about "MG training" -- what it actually says is "By now you chowderheads have had some experience with SW and fired a machine gun or two.". But you're right, as far as I can see, the only interaction with SW up to this point is portaging a MTR. Mind you, I didn't read the examples line-by-line.
Chapter K was an experiment from way back in the early days of ASL that was deemed only partially successful at best; some folks found it valuable, but many didn't. It was an attempt to counteract the "reference only" nature of the main rules. Personally, I think it contains some information that might be helpful to an absolute newb, but is no substitute for learning-by-playing.