A lot of confusion is spread over what does what and why in paintball, in this section I will try to clarify some of the concepts and explain what parts do what.

Bolt - Bolt in every paintball marker is the part that pushes the ball out of the chamber into the barrel and shoots it out with a brief surge of compressed air or co2. The only reason why you would want to upgrade your bolt is to get a lighter one which would allow the marker to reach higher rates of fire, this would go hand in hand with getting a lighter hammer. There are several basic bolt designs:

Aluminum with O-rings - this usually comes standard with the marker and usually is a good design, it is heavier than delrin but if your marker is non-electronic it doesn't really make a difference. Some well milled aluminum bolts are much better than any delrin or other type. Basically what you are looking for is a free flowing bolt which will allow maximum amount of air to pass through it and apply that to the ball, also the face of the bolt should be cupped on the edges so the edges grab the ball gently without hitting it hard with a straight edge.

Delrin without O-rings - Delrin is called "self lubricating" material, a bolt cut from delrin without o-rings is basically a long hollow tube what fits instead of the orignal bolt, it is lightweight but on many instances delrin will absorb some of the oil/lubrican from the merker and swell up jamming itself in the marker.

Delirin with O-rings - Delrin is a very light plastic like substance, a bolt cut from delrin with O-rings is a good replacement for an aluminum one, especially if you have an electronic marker this upgrade should help you speed up markers cycle.

Nylatron without O-rings - famous (or infamous) Shark bolts were made from this material, it is basically like delrin (light and plastic like) however the big property was that it does not swell up when in cantact with marker oil, this is not always true.

Venturi bolt (Aluminum or Delrin) - venturi technology comes in many different designs however the concept is that it breaks the air flow into many sections so that there is no turbulence or uneven flow of air, this means that the ending of the bolt where the ball makes contact has either many tiny holes instead of just an open space, or has a divider which divides the airflow into 2 section, 3, 4 , 5, 6 ect...so we end up with even amount of air hitting the ball and causing it to fly straight. This is a highly disputed fact since some tests prove that it works and some prove that it is only an air restricting modification where you want your bolt to be as free flowing as possible. Perhaps some designs work better than other but every company making a venturi bolt claims it to be the best.

Drop Forward - is an attachment to the bottom of the gip frame which will move the tank ASA forward and down which will allow for better marker balance. It can be in a form an arc, or small bend or a long piece of metal, some come in blocks and with carved flames. Over all if you plan to run with a heavy tank you should have your marker balanced for easy manuvering. Sometimes a dropforward will have an On/Off valve allowing for turning of the gass supply. Drop forward works with a tank, if you plan on using a remote line do not invest in a drop forward.

Expansion Chamber - this is for markers which use CO2, CO2 is stored in liquid form inside the tank and the liquide can flow through the marker and get to the ball freeze it and it can shatter in the barrel. Expansion chamber consists of series of small diamond or cone shaped compartments in which the liquid CO2 expands to fully gassus form and not harm the ball or any other marker parts. Expansion chambers come in 4 or 6 or 8 compartment versions and also are making for great grips. Come to think of it if you could fit an ION with an expansion chamber as well as regulator you could actually run on CO2. <see my ION review> Also remember, by no means a through grip or gass through grip should never be compared or considered an expansion chamber. See gass through grip description.

Gass Through Grip - is basically a replacement hose in a handle format. It is a solid piece of aluminum with a hole drilled right through it. It is a grip or additional handle on your marker which doubles as a gass line. They are good and decorative but for extra 10 bux you can have an expansion chamber and for extra $25 you can have a used regulator.

Hammer - in the blow back world the hammer is a very important piece in the marker, it hits the valve opening it briefly which results in the high pressure gas reaching the ball and at the same time cocking the marker again

Hose (Braided)

Macro and Micro line

Regulator

Remote Gass Line