How to check the condition of a used handgun--general points
Before handling any firearm, always open the action and verify that both the chamber and the magazine are empty. Remove the magazine if possible. Every time a firearm changes hands it should be cleared.
1. Look at the overall condition of the gun. Notice the condition of the bluing and the overall wear. Look for rust pitting on external metal surfaces. Are the grips in good condition? All screws should be tight and the screw heads un-marred. The gun doesn't have to be perfect in every area, but it should show care rather than neglect. A pistol could be rough on the outside, yet perfect on the inside, but the chances are that an owner who didn't care for the external parts of a gun also didn't care for the parts you can't see.
2. The size, shape and angle of the grip should fit your hand. When you bring the gun to eye level your master eye should be looking straight down on the barrel. The gun should not be tipped up or down. Having a gun that points naturally is especially important for a pistol that might be used for protection.
3. Look carefully down the external length of the barrel to see that it looks straight and there are no subtle bulges. Don't buy any handgun if you suspect that the barrel (or the cylinder of a revolver) has been bulged, no matter how slightly, or if it is not straight. Also look at the crown of the muzzle--it should not be dinged.
4. Note the position of the rear sight on guns with adjustable sights. If it is way off to one side, suspect some sort of problem and ask to shoot the gun to verify accuracy before purchase. If the seller refuses, pass on the gun.
5. Check the condition of the grips. There should not be any splits, chips, or cracks in the grips, particularly if you are looking at a discontinued model (for which it may be hard to find replacement grips). Scratches in the grip finish, worn checkering, and tiny nicks in the grips will not affect the gun's function, but should lower the price.
As the screws holding wood grips to the grip frame are tightened they will tend to pull deeper and deeper into the wood. Check to see that they are not about to pull clear through. This is particularly common with Ruger single action (SA) revolvers, but applies to most guns with wooden grip panels.
6. Get permission to dry fire the gun and check the trigger pull. Dry firing will not hurt most centerfire handguns, but it is still a good idea to use snap caps to protect the firing pin.
Whatever the trigger pull weight, it should be consistent from shot to shot. If it feels like a stock factory trigger (too heavy with some creep), fine, you can get it adjusted later. If it feels crisp and breaks at 2.5-3 pounds it has probably been worked on or adjusted. This is great if done properly, as it will save you some money, but make sure that the piece will not jar off.
To test this, get permission to bump the butt of the cocked handgun against some firm but padded surface. The gun should not fire. Push against the fully cocked hammer (if the pistol has one) with your thumb--it should not slip out of its notch; reject the gun if it does.
7. Check the inside of the barrel (and the chambers of a revolver's cylinder). If the barrel is dirty, ask that it be cleaned or for permission to clean it yourself. Do not oil the barrel after cleaning, and be suspicious of any barrel that has been oiled. The shine from the oil can hide minor barrel imperfections and pitting.
Once the barrel is reasonably clean, dry, and oil free, open the action or remove the barrel and look into it from both ends. Use a bore light. Hopefully it will be clean and bright with sharp rifling. A slight amount of rust or pitting inside the barrel (or the cylinder of a revolver) will ordinarily not seriously degrade the performance of a handgun, unless it is a target pistol, but it should lower the used price.
Specific things to check on used revolvers
1. Note the condition of the forcing cone at the back of the barrel. Slight erosion in this area, particularly on magnum revolvers, is not cause for concern, but it should not be seriously eroded. The more erosion you see the more the gun has been fired with heavy loads.
2. Check for cutting of the top strap at the cylinder gap, particularly with magnum revolvers. A little erosion here will not hurt, but excessive cutting is undesirable and indicates a lot of shooting with heavy loads, or a wide cylinder gap, or both.
3. To test the safety notch of a traditional single action revolver, pull firmly (about 8-10 pounds--this is not intended to be a test to destruction) on the trigger with the hammer in the safety notch to see if it can be easily forced. Put the revolver on half cock (the loading position) and repeat the test, applying about 5 pounds of pressure on the trigger. The hammer should not drop. This test does not apply to New Model (two screw) Ruger SA revolvers, as they use a different lockwork than traditional SA revolvers.
4. The cylinder of Colt double action revolvers should be completely tight when the trigger is pulled all the way back (the hand forces the cylinder against the bolt). S&W revolvers are never as tight as a Colt, but at least they should not rattle. Slight cylinder play is permissible with S&W DA (and also Ruger SA) revolvers.
5. Check the cylinder gap. It should not exceed .010", and .006" is ideal. Cock the gun to turn the cylinder so that every chamber, in turn, lines up with the barrel. The cylinder gap should remain constant.
Also, the cylinder should not slide back and forth appreciably on the cylinder pin. This is called endplay, and it generally increases with use.
6. The crane of a swing out cylinder DA revolver should fit tight to the frame (when closed) without any unsightly gaps. If it doesn't the crane may be sprung. When you wiggle the cylinder with your fingers the crane should barely move, if at all.
While you are at it, check to make sure that the ejector rod has not been bent. This is easy to see if you spin the cylinder, which should spin true.
7. Use you fingers or thumb to put a small amount of drag on the cylinder while you manually cock the revolver (single action mode). The cylinder bolt should click into the locking notches in the cylinder, locking the cylinder in place, at the end of each segment of cylinder rotation. If it does not, the gun is out of time and needs work. Then rapidly thumb cock the gun (don't "fan" a revolver)--the cylinder should not rotate past the proper locking notch. Also, the bolt should not be dragging on the cylinder as it turns. If it does it will leave a clearly visible wear line in the cylinder's finish.
8. Examine the sideplate of a DA revolver. If it has been improperly disassembled it may show pry marks at the edge or have been warped. The sideplate should fit flush and tight, without any gaps.
9. Check the tip of the firing pin, it should be smooth and rounded, not sharp or broken. The firing pin hole should not be chipped or burred.
Specific things to check on used semi-automatic pistols
1. See that all of the controls work smoothly and with a reasonable amount of pressure. The safety should prevent the gun from firing (check by setting the safety and pulling the trigger normally). The slide lock should hold the slide open. The magazine release should release the magazine easily and yet hold it securely in place until it is pushed. If there is a grip safety the gun should not fire unless the grip safety fully depressed. If there is a magazine safety the gun should not fire unless the magazine is in place. Also, pulling the trigger should not fire the gun when the slide is held slightly out of battery.
2. Cycle an autoloader to verify that it operates smoothly and properly. See that the slide is tight and reasonably free of slop when closed and the pistol is cocked. (There is ordinarily some play or the gun will not function.) Verify that the pistol fieldstrips and reassembles correctly. Also see that the action has been kept reasonably clean for proper functioning.
3. Examine the slide (especially at the front and at the ejection port) and frame for excessive wear or cracks. Aluminum alloy frames are particularly susceptible to developing hairline cracks (and eventually failing) from extended use.
4. The cocked hammer or striker of a SA auto pistol should not drop when the slide is closed smartly. If you can make the hammer drop by letting the slide slam closed the gun is unsafe.
5. Check the magazine(s) for wear and condition. A proper magazine is very important to the functioning of an autoloading pistol. You want the original, name brand, magazine(s) in good condition. Inspect the feed lips for bends, cracks and wear, and insure that the seam at the back of the magazine is tight.
Also check the bottom of the magazine to insure that it has not been ejected from the pistol and allowed to fall to the ground. This looks great on TV or at action matches, but in real life it is very hard on magazines. Magazines are not expendable.