Problems with guns

In the post-apocalyptic world of my WIP, the villain wants to get hold of a gun. With no police or legal system, a man with a gun is top dog and can get away with murder. So I did some research on guns. 

London's Metropolitan Police authorized firearms officers use Glock 17s. As my novel is set in London, that's the most likely gun to be available. A Glock 17 is semi-automatic, and has seventeen cartridges in the standard magazine. They are extremely reliable and don't go off if dropped. Pulling the trigger deactivates the safety catches. Fine so far. Then I did more research (so easy with Google - writers are spoiled these days).

When a gun is fired, the noise is 140 - 160 decibels. Loud enough for one shot to permanently damage the hearing of the firer and anyone close by. (A silencer will bring that down to 120 - 130, not actually all that silent as it is in movies.) I found some worrying forums where young men had fired a friend's gun a few times and were asking whether the tinnitus and muffled hearing they now experienced would ever go away. Watch any action film, and you can understand why people don't realize the danger; heroes without ear muffs/plugs shoot away like mad, are shot at, then don't spend the rest of the film with most of their dialogue consisting of, What was that you just said?

I also discovered that you need hearing protection if you are going to spend more than fifteen minutes on a snowmobile (100 decibels). My characters do that. So I have a choice between irresponsibly promulgating the idea that guns and sleds don't require earplugs, or holding up the action with a Health and Safety message. 

Rats.