You don't want to hear this, but you are probably going to become very well acquainted with that garage floor, and all the little nooks and crannies where it could have settled after a few ricochets. I recently lost a rifle firing pin spring retainer clip in my bedroom, and found it across the room from the wall it hit. I take my pistols apart inside a big plastic bag, but with my luck, something will probably pop out the top. Hope somebody can steer you to a parts source.