Why does my nailer keep miss firing? Finish nailers need to be properly maintained if they’re going to be reliable and not have miss firing. The easiest way to have a reliable nailer is to keep it lube before and after every use. Use LIQUID WRENCH® Lubricating Oil in the bottom of the gun before and after every use to keep it lubed, protect against corrosion and wear. It also displaces moisture, so it’s ideal for long term storage.