Most are stolen. Taking out the storefront robberies where there is almost no security and it's all just glass windows, display cases, and a whole lot of effort to put guns in a safe - yeah, real good thinking there - the rest come from - you and me.
Home breakins, and thefts from vehicles or the entire vehicle. Under 21 ransack neighbor's cars constantly for items to sell for drug money, a gun in the door pocket or glove box? That is the reason why some politicians want to increase penalties for unsecure guns, and you and me GIVE them the ammo to push for it.
Home theft is just as bad and outlying homes unattended during the day a prime target. White van in the drive must be a home repair guy. Yeah, sure, and in most cases, the homeowner showed them the guns 6 weeks previously when they hooked up with one of the kids and came over chillin - to case your house. Then later their dad or the lead gangbanger went with them at just the right time, done. Gun safes slow a lot of that down, get the idea you are on vacation and they have the time.
These guns aren't being stolen out of the mail, Postal Police are on that a lot, plus packages are tracked. Some are going out the back door of retail, but the owners are also watching for that. Some go out the front door, I saw a stainless. .44 Smith disappear from a locked case at Montgomery Wards at our mall in the day, they simply pried up the glass top case with a pocket knife, took three steps and out the side door. Not secure at all. Stupid, in fact. We have more secure video card exchanges with rolling grilles here than secure gun keeping in stores. The local FFL had his window smashed late one night, a dozen guns taken. They showed up 125 miles away on Craigslist. That didn't turn out well for them. Add the parking lots full of gun stickers on cars and trucks saying "rob me."
A lot of people online tell us they leave guns in cars 24/7, yet very few admit to having a gun stolen because of it. Oops. there goes $500 - 1,100 with holster and ammo. Tragic boat accident is beginning to sound like "My gun got swiped I'm hiding the fact." Sorry, guns in places like Chicago are YOUR guns. I'm doing what I can to keep mine out of their hands.
1) Don't leave guns in vehicles, ever. If that is an issue for some, then either don't go with a gun, or spend the same amount of money on a gun safe. We justify spending the same as the gun on an optic, but it's ok to not spend the same again to keep it? Naah, just drop it in a door pocket or the console. And those are the first places someone looks when breaking into your car.
2) Don't leave guns in unlocked cabinets in the home especially the same old ones we always talk about all the time here. Of course it's called a nightstand gun, - that's where to find it. Feed your dog enough over weeks at a time and ol Rover is waiting for his handout, not barking at an intruder. Even more, have a schedule where the house is unoccupied, and even worse, unseen from the road, and you have a recipe for disaster. The workers you have around doing repairs and chores may be a reputable company, however, some of the actual laborers may be feeding tips to their cohorts. No, they don't show up, they have a cover. No, you do NOT give them your house key so they can dupe it at the Walmart key machine. In fact, it shouldn't even be a key blank offered. And NO, you don't trust electronics, they do not work without electricity, which is super easy to cut. And you do put up security window film which will withstand them throwing blocks and rocks all day and not get in.
Gun security is more about don't ask don't tell, chase off that nosy guy at the range, keep the neighbor kids clueless about your guns, keep their older brothers off balance about your schedule, and keep their handlers out of your stash by hardening the home. You will be better off, grandpa's Luger or 1911 will stay put, and one less gangbanger in Detroit will bite the dust from your carry gun you forgot and left in the truck. You and I are the gun sources they use, don't be that guy.