PPW holders will be people who have had specific, verifiable threats made against their lives - so will often be people with links to violence, terrorism, or criminality. And, obviously, the unlicensed users are criminals by definition.

So, on balance, the average weapons owner in NI is probably more dangerous than the equivalent in the US. I do agree that it's hard to make anything more than a very general comparison between the two very different situations, however.

By comparison in my county in Washington state, there are 114,000 active concealed firearm permit holders out of a population of 2.3 million. And this is a liberal, fairly urbanized region.

We're talking ~50x the rate of people carrying firearms legally. Of course data on criminals carrying weapons is not so transparent, but it's suffice to say that American police are much more regularly encountering people with firearms.