A couple weeks ago I sold my Glock 23 gen 4 on Armslist. I never really planned on selling it but then too I rarely shot it. Put it on AL and it sold rather quickly. Sale went fine and the person seemed to be a nice younger individual. Transaction was done by the book and everything checked out correctly with paperwork. Two days later I get a text asking what ammo the gun shoots. Me: I found Gold Dots worked very well and highly recommended he try those. Him: what mm is that? Me: not sure what you mean by mm? Him: What mm size? Me: 40 S&W if you're asking what caliber? Him: You sold me a Glock not a S&W. What size mm? I thought he was just trying to be funny but the conversation continued and I realized he was totally serious. I really wanted to help him understand but finally recommended he bring the gun in to a dealer for some help to make sure he gets the correct ammo. It kind of made me think holy shat.