The reason, originally, for the 3rd amendment to the constitution was because the original United States did not have a standing army. As a result they needed to be able to call to arms, at short notice, enough armed personnel to repel any attack, as it were. They were rebels, who had rejected rule from the UK and as such, despite declaring their independence, were still under threat.
I too am not particularly interested in guns, however guns do play a part in Sherlock from Moriarty seemingly identifying the gun Sherlock carries in TGG, John's use of the gun to shoot the cabbie in ASiP, the snipers in TRF and Moriarty's suicide etc. what threw this into my field of vision, as it were, originally was Moriarty's
'identification' of the gun before he could see it in TGG.
Whilst I may not agree with the principle of everyone's right to carry arms, we have very strict gun laws here, I respect the right of citizens of another country to think differently about it; although I would hope that this might change in future. In the UK, as I said, we have strict gun laws but that does not prevent random shootings, massacres, gangland shootings and guns being used for robbery etc. It is not just a case of having strict gun laws because not everyone respects the law anyway. Knowing about guns per se, not even knowing how to use one, will necessarily cause a problem. Guns don't kill, people do.
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Don't make people into heroes John. Heroes don't exist and if they did I wouldn't be one of them.