It would be excellent for a Glock slide. You will need to tape off the the inside dovetail cuts because it will add dimensions. The rails on the side of the slide will be ok. Also tape any lettering with very thin non sticky tape and spray those areas lightly at the end. The lettering on the slide is so fine it is going to be hard to keep from filling it in. If you hold the can way back and dust it that will probably work. I would say practice on some scrap metal. You can put a scratch in the metal about as deep as the lettering on a Glock and see what happens.