Just received my The Complete Glock Refrence Guide and decided to clean my slides. All three of my slides are used and I had no idea if they had ever been thoroughly cleaned. My 27 was dirty with metal shavings and what I expect is the typical crud. My 19 was identical to my 27 in terms of debris. Now when I stripped my 23 something was different. I noticed deep in the firing pin hole debris/metal flush against the bottom of the hole next to the firing pin slit. After inspecting the firing pin there is noticable wear in the where the firing pin safety engages the firing pin. My first thought was milling debris never cleaned out but after thinking about it I think the safety is wearing the firing pin. This was purchased used so I have no idea of round count. Does not appear to have been through the ringer. It is a 3rd gen. for what it's worth. I will replace the safety and firing pin but am trying to cut my teeth on my Glocks. Just joined the GSSF and can't wait to take the Armorers class.