Buying a used gun can get interesting. You can never really tell what you have until you go shoot it. Will it work? Did you buy a lemon from some creep? It can be hard to tell if you don't know what to look for. Let me give you some tips.The exterior can tell you a lot. A well warn finish says a lot about the age of a gun. However, I've had a lot of guns in front of me that looked horrible but had been well maintained and worked flawlessly. Test the actions. It sometimes helps to look away or close your eyes while doing so. It forces your other senses to do all the work. Does the action feel smooth or does it feel gritty? As you move the action slowly does it sound right? You know what your current guns sound like. If this is your first gun I know you've been at your local sporting goods store doing your homework and have heard the sound of new actions. A used gun should not sound any different. Smoother, cleaner...sure but that should be the only difference between the two. All the same sounds should be in the same order. You will be able to tell if the internal springs are in good shape by the volume of the clicks inside. If you hear strong clicks, for instance while pulling back the hammer, you know the springs still have a lot of life in them. If it sounds muted and lethargic then it will need repairs soon if not right away. Weak springs may not have enough energy to discharge the gun.

Ok, you know how to listen and what to listen for. You want strong movements and no grit to the sound of the action. Let's talk about aesthetics. No one likes an ugly gun but I'd rather have an ugly functioning gun than a broken work of art. Besides ugly guns are easy to fix up. What you need to decide is how much, if any, you want to put into a gun to make it look the way you want it to.

Rust comes in several degrees. You may see some faint spots under the bluing. (They look like they are underneath the bluing anyway) This is the first stage of rust. Still truly not a big deal, though. Even after the spots penetrate the bluing use some gun oil and some 0000 steel wool. The spots will come off, the gun will not be scratched, and the bluing will not be rubbed off. However, use a more coarse steel wool and you will have scratches and removed bluing. Just be careful. Pitting is a much more advanced stage of rust. The small spots have started eating away at the metal. There is no way to remove the pitting without removing the bluing.

(Rust beginning to pit, still minor though)

The pitting can be deep enough as to degrade the integrity of the gun itself. Pitting too extensive and too deep will make barrels and actions dangerous. The good news about this is that one that bad is rare. Think of things this way the chamber pressure of a .22lr is 42000psi. That's a lot of pressure for anything. This is why structural integrity is so vital.

(Rusty crown rusty bore, the crown can be fixed. The bore...No.)

All that in mind, take into account what you want aesthetically, how much you are willing to put into each gun to get it the way you want, and if a particular gun is worth is. Your gut won't lead you astray.

Our next issue still has to do with rust and pitting but has nothing to do with aesthetics. Now we are talking about the bore. If you are looking for something to have re-barreled this section doesn't matter. For the rest of us here is the key, go get a bore light. For just a few dollars you can buy yourself a lot of peace of mind. That's because the bore can rust and pit just as easily as the outside of the barrel. It is quite difficult to see pitting by looking down the barrel alone. With the added light of the bore light the condition of the bore will be plain to see. A pitted bore usually means a rusty or pitted barrel crown too. This is a lethal combination for accuracy. If you are not looking for a gun to have rebarreled then a gun with a pitted bore is a poor investment.

All these considerations should lead you to make good decisions with used gun buys. Of coarse it is always a good idea to have used weapons checked out by your department or platoon armorer, or your local gunsmith. They might find something you missed that needs attention.

Now there's no longer a need to fear the used guns you've been shying away from. So, go out there and make the pawn shop or gun show your friend.

Gun shows around these parts require the action be prevented from opening, usually with a plastic wire tie through the trigger guard and the ejection port on a pistol, or around the back of the hammer on a revolver.
Pain-inna-butt. No way to check much.
Makes it hard to want to buy used at a show.

Bring a pocketful of your own ties. That way you can cut one off to inspect the chamber and bore, and put a new tie on when you're done. If the seller won't agree to that, walk away.

I think the number one thing is: know what you are buying!  If you are looking for a DA Colt know how to check the timing and know that MK IIIs and Mk Vs are different than a Python.  If you are looking at a CETME/G3 know how to check head space and what to inspect.  Do you know about Winchester 101 firing pins, M1912 adjusting collars, '03 Springfield heat-tread issues?

Some things I won't buy on Gunbroker, like Colts, because I don't want to spend $$$ on a gun and have to spend more on a timing job.  You have to know what you are.  It it important you be an informed consumer and be knowledgeable about what you are buying before you drop your scratch on that new arm.

While I agree whole heartedly with the wisdom on this thread, sometimes you get lucky.  I purchased a T53 Chinese Mosin variant from Omega awhile back, see posting in rifle section, for 55.00 + 15.00 shipping.  First thing my wife said when I opened the box was "are you really going to shoot that?"  Looks wise, I couldn't blame her.  It was ROUGH! Thought I was out of luck, bore was dark, I mean dark, stock was just sad looking, bluing gone in several spots.  Used some tough love on the bore, and while still dark, did see the beginning of lands and grooves.  Took it to the range, loaded a round of 1950 Bulgarian HB, held it away from my face, and BOOM!  Everything was still together, ejected the case and loaded another.  Shooting in the area I was aiming, and got better the more I shot it.  Got it home, gave it some more tuff love w/Ed's Red, and by golly, there was a rifle bore in there!  Turned into my best shooter until I picked up my 91/59 at a local pawn shop.

(your results may vary, the poster is not recommending this in every case, WTA, it's Staff, and management are not responsible for the content of this post).