I am not stuck on the "military thing". The military should have the
most lethal weapons available.
I am stuck on military type AR-15s available for civilian purchase
because they have a record of being the weapons of choice for these mass
shootings more often than not. I don't know why they hold such a
fascination for nut cases who want to go kill a bunch of people but they
do. Maybe it's because they are cheap, heavily marketed and available
as you have pointed out.
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I think the high capacity magazines have a lot to do with it, along
with relatively small size, high power and reliability.