Use strange parts if you want to see your strange killing stats. This includes killing by head-shot, or buildings that you have destroyed. TF2 strange parts is a one action item that players apply to their weapon to get a strange stat.
You can use three parts to one weapon to get different stats. Want to customize your weapon, but don't know where to buy strange parts TF2? DMarket offers the best deals to buy or sell strange parts in Team Fortress 2.