Of democracies with guns I think Switzerland is probably the best example.
There are some key differences between Switzerland and the US
1. It's ethnically and economically pretty homogenous
2. There is mandatory military service
3. It's culture is defensive, given it's history.
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In the US the 2A argument as we know it is very recent... 2000s
prior to that cases went way different.
United States v. Cruikshank said that the 2A didn't apply to individuals, and therefore it was legal for the paramilitary KKK to deprive freed slaves/black American's of their firearms. So 1875 America 2A didn't apply to black American's according to the supreme court.
United States v. Miller Essentially a firearm had to be for military use to have the 2A apply, and didn't apply carte blanche to all firearms.
"The Court cannot take judicial notice that a shotgun having a barrel less than 18 inches long has today any reasonable relation to the preservation or efficiency of a well regulated militia, and therefore cannot say that the Second Amendment guarantees to the citizen the right to keep and bear such a weapon."
Then there is the Mulford Act attempting to disarm the black panthers.
Point being we have about 20 years of the current outlook on the 2A and about 10 years of everyone having AR's.
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Sorry for the digression, here's my main point with Switzerland, the main issue the Swiss are worried about is being invaded. On this thread that's been mentioned very few times if any... who is going to invade us? The main context of the US 2A is inward defense against each other.
Personally, I'm not sure if everyone being armed against each other is good long term for democracy, doesn't exactly lead to spirted dialogue and compromise.