Who says there has to be only one of measuring things? Metric in my opinion is stale and conformist but admittedly useful especially in scientific calculation. Imperial on the other hand is rich, cultured, arcane, complicated and has a certain inconvenient elegance that I wouldn't give up.

Some good comments, but also some huge assumptions, like "pro-gun types actually believe that guns have magical powers to imbue people with good judgement...." Where does that come from? I don't think it is true at all, besides which it presumes that you are either able to read others' thoughts or have conducted a survey.

I think, as a pro-gun type myself, that pro-gun types simply reason that possessing firearms is a good means of defense. If one will agree that self-defense is sometimes a necessity, there is nothing unreasonable about believing that the most effective means of self-defense should be available. Just because a gun may not always be effective is not a distinguishing characteristic of its employment: running away, a knife, screaming, etc. are all also not always effective. The "pro-gun type" simply believes that the gun is more likely to be effective than any of these other means. He may also believe that he has a right to the means, which with I agree, but that's another argument.

Does having a gun actually make me safer?

Only if you keep it loaded and accessible (i.e. on you).

Am I more likely to prevent a crime with it, or is it more likely that it will enable / escalate one?

Depends on your own lawlessness or lawfulness. Obviously, the consequences of pulling a gun are enormously high. We are talking life and death situations. I'd rather have the gun when I don't need it rather than not have it when I do.