Barrels come in the bewildering array of shapes, materials, and weights, and once you have found the perfect dart for you, this is the part you should never have to replace. It is also the most neglected part of the dart when it comes to maintenance. Your darts will get dirty no matter what. It could be the natural grease from your skin, the salt and grease from bar snacks, you could have been picking your nose while waiting your turn, or you foolishly set them down on a beer-soaked bar table. When we talk about a difference of as little as one gram in dart weights, your own fetid filth can easily add unnecessary weight to your dart. Wash your darts barrel in a mild soapy water to keep them fresh as a daisy, and shiny as a new penny.
Darts Barrel shape
The barrel forms the main part of a dart. When we are speaking of "buying a (new) dart" we mean getting a new dart barrel. Nowadays barrels are available in almost every possible shape, with a wide selection of knurl or rings on the surface for a comfortable and safe grip.
The main barrel shapes are:
It's not possible to say which one is the "right" one. Based on a very theoretical reasoning the long cylindrical barrel could be the best of them because it is the slimmest and allows the tightest grouping. Good for 140s and 180s. But this reasoning doesn't help you when you are not able to handle such a barrel. Selecting the right shape is a matter of personal preference. Choose what feels comfortable for you. This is much more important than an abstract or "academic" reasoning about theoretical advantages or disadvantages of some shapes.