New guns are expensive items to buy, and they're only getting more so. One question I get asked all the time from my students is why not buy used. I myself have bought many used guns, but I've also had a couple of duds. With used guns you're almost rolling the dice. You can get a fantastic deal, but you have to know what to look for otherwise you could end up with an unsafe piece of gear. But with the right approach and a close inspection, you can find the diamonds in the rough.
I'm personally a sucker for a deal.
One of my favorite firearms to this day is a steal I found at an old estate sale. I rather enjoy poking around yard sales when I've a Saturday morning free, and on this particular morning I noticed a small handgun in a cigar box that had obviously been neglected in the back of a cupboard for decades. Surrounded by more rust and rat droppings than anything else, I picked it up for under $100, and after putting it through the works I was surprised to see the internals had been well looked after (for the most part). It was an old colt six-shooter, and I still feel like a cowboy when I shoot it.
But enough about that.
When you're buying a used gun there's a few red flags to watch out for.
Always, always, check it's not loaded
This should be a given, because far too many people don't follow the rules for good gun safety. Before you do anything with someone else's gun, check that the gun isn't loaded. It's just common sense, too many things can go wrong once you start inspecting the gun if there's a round in the chamber. And I don't want there to be any accidents. Safety first people.
Just how much rust there is
With metal firearms you're always going to find a little rust, but that's not a deal breaker. What you want to watch out for is the deep, pitted rust that shows it's been neglected for years. I'd never recommend buying a firearm if there's massive damage to the metal. Surface rust you can clean off with a simple handgun cleaning kit, so take a good look at the overall condition of the gun.
Looking for any obvious imperfections
When you're considering the purchase of a used gun, you want a jewelers eye loupe to really investigate the condition of the firearm. Pay attention to any cracks, deep scratches in the metal, or any obvious imperfections that may hinder the guns performance. If the final finish is a little worn that's fine, but anything else would be a red flag for me.
Looking down the barrel and the muzzle
Take a look at the end of the muzzle, if it's all roughed up it probably means it's not going to shoot right. You also want a light to look inside the barrel at how many lands and grooves are inside. It's unusual it'll be shot out, but there's always a chance so look closely. A flashlight will help immensely here.
Looking at the screws on the gun
If someone has treated their gun a little rough, you'll notice it in the heads of the screws. If they're burred or warped, it means they've actually removed key pieces of the gun (like the side plate on a revolver), and then you need to wonder what they've fiddled with inside. I'd avoid it. God only knows what they've messed with internally, especially on a semi-automatic.
Feel the trigger press
Once you've shot your fair share of guns, you'll get a feel for the "right" amount of tension in the trigger. Too light, and you know someone's messed with it. Too much movement, and you could be facing a misaligned cylinder that isn't good either. There should be no wiggle room between the forcing cone and the cylinder when it's all closed. On a semi-automatic, make sure to also check the hammer follow through while holding the trigger pressed. If it follows the slide when you're re-racking, it's definitely going to need some work before you can safely shoot it.
Feel the play in the barrel
With a semi-automatic there's just so much that can go wrong, but one of the things you can notice is the play in the slide. If you hear a rattle when it's shaken, that's a bad sign. You should also not be able to press down on the barrel hood and get it to move too much. Tighter is better.
Buy from a reputable dealer
Now the final piece of advice I can give is this. Buy from a reputable dealer. Most will have a store policy where they stand behind the guns they sell, which gives you an added reassurance when considering a used gun. Usually they'll throw in a good cleaning, and will offer a limited warranty to repair or replace any malfunctioning parts after the sale. At my local gunsmith they offer a 30 day warranty on any sale, and will replace any used gun with store credit if it doesn't shoot safely.
Buying a used firearm isn't as dangerous as people think. In fact, it's a smart way to arm yourself without breaking the bank, so long as you know what to look for. The trick is to inspect the weapons thoroughly, and be willing to wait for the right deal. Shop around, and only buy a gun if it feels right.