a) The State needed a well-trained militia
b) The militia consisted (at least theoretically) of every male over 18 years old
c) There was no time to train people to shoot when the militia was called out to respond to a threat
d) Therefore everyone needed to have acquired and to keep maintained throughout their lives shooting skills, and
e) Therefore everyone needed to own a gun so that they'd already know how to shoot if they had to be called out to defend their communities or their country.
I had figured the concept was:
a) The State needed a well-trained armed (what "well regulated" meant at the time) militia
b) The militia consisted (at least theoretically) of every male over 18 years old
c) There was no time to train people to shoot when the militia was called out to respond to a threat
d) Therefore everyone needed to have acquired and to keep maintained throughout their lives shooting skills, and
e) Therefore everyone needed to own a gun so that they'd already know how to shoot if they had to be called out to defend their communities or their country against threats both foreign and domestic (domestic threats included criminals and wanna-be tyrants).