Ok. We've all been there. You look into a display window and see a nice semi auto that you really like. You notice that it's used. You would purchase thise weapon because of the cheap cost, but you aren't sure if it's a "lemon" or a good running gun.
Here's some quick tips to help you out. The weapon used in these pics is my personal Smith and Wesson SW40VE Sigma. This pistol is used, and has tons of medium to high power .40 rounds through it so far.
1. Check the area where the exposed portion of the barrel meets the slide. If it's used, you should see some wear, but there shouldn't be excessive pitting, cracks, or gouges.
2. Check your sights. If the sights are broken in any way, then it would be wise to put the pistol down and look for something else. The sights should be clean, tight, and should align easily when obtaining a correct sight picture.
3. Check the condition of the feed ramp. There should be no cracks, pitted areas, or missing sections.
4. Check the breech face of the weapon. There should be no cracks or pitted areas. The extractor/ejector should not have cracks, and should function correctly. The firing pin hole shouldn't look like it's overly large.