Paintball Gun Review

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Confused about Paintball Tanks? They're one piece of equipment you can't live without.


PMI 20 oz CO2 TankCrossfire 68/4500 HPA Tank







20 ounce PMI CO2 tank (left), and Crossfire 68/4,500 HPA paintball tank (right)


CO2 or Nitrogen/HPA?

Your paintball gun is powered by cylinders of either CO2 (carbon dioxide), or nitrogen/HPA (high pressure air). Nitrogen and HPA is the same thing as far as paintball guns go, since air is made of 78% nitrogen.

The cylinder is usually attached directly to your gun, or carried on your back or side, and connected by a "remote" hose.


CO2 is the cheap way to go, but it has its problems. Because CO2 becomes a liquid when compressed, it needs to expand to a gas before entering your gun, otherwise the liquid CO2 can damage the rubber parts and O-rings, and you can see snow out the barrel.

This expansion causes the tank to cool as the liquid CO2 turns into gas, and eventually under sustained fire, and especially in cold weather, the liquid CO2 will not evaporate into gas. It will freeze your gun, and it won't fire again until it warms up. This may take 15 seconds or more, enough time for you to be shot.

Another problem with liquid CO2 is that it causes variation in the speed of the paintball, causing inaccuracy, especially with rapid fire. As the CO2 tank cools, its pressure drops, and lower pressure means less distance traveled.

One benefit of CO2 is you can get more shots out of a CO2 tank than you can out of HPA. You might shoot 7 hoppers of balls from HPA, and 10 from CO2.

There are several ways to keep liquid CO2 out of your gun. An anti-siphon valve can be placed inside the tank. Or, an expansion chamber ("x-chamber") can be used to change the liquid into gas. Or, you can remote the tank using a hose to give the liquid time to expand in the hose. Finally, you can use a regulator.  Keeping liquid CO2 out of your gun will also give you more shots from a bottle.

CO2 tanks are specified by the number of ounces they can hold, e.g. 4, 9, 12, 14, 16, or 20 ounces. Do not confuse with 12 gram cartridges used for side arms.


When nitrogen is compressed it remains a gas. When it expands it also cools the tank, but at an unnoticeable rate because it does not have to transition from liquid to gas. Therefore it is viewed as a superior source of propulsion. However, because HPA (High Pressure Air) is stored at up to 4,500 lb/inČ while liquid CO2 is stored at 1,200 lb/inČ, tanks for HPA are more expensive. Nitrogen tanks can either be filled with pure N2 or compressed air.

Nitrogen and air systems are more expensive, and are preferred to CO2. These air sources are primarily used by people who play often and have tournament-grade markers.

Steel HPA tanks weigh more than fiber wrapped tanks and are more expensive. They perform the same, but steel tanks only come in 3,000 PSI versions. You will get more shots from a 4,500 PSI tank. HPA tanks can be filled from a scuba fill station, but not from a typical compressor which only produces about 125 PSI.

Nitrogen/HPA tanks are specified by two numbers: cubic inches (e.g. 48, 68, 72, 88) and pressure (e.g. 3,000 or 4,500). These are often stated as 68/4500.

HPA tanks come with either an adjustable or preset regulator. An adjustable regulator allows you to fine tune the output pressure (typically 200 to 1,000 PSI) to optimize your gun's performance. A fixed regulator is set to one pressure, typically 800 PSI.

Low Pressure (LP) vs. High Pressure (HP)

Most markers run at high pressure (about 300 - 1,000 PSI). These include Automags, Piranhas, Spyders, Angels, and most Cockers. Some markers run at low pressure (about 100 - 300 PSI). These include Shockers, Impulses, Matrixes, and others.

Tips for Choosing Your Tank

• Most fields have a fill station with CO2. Some also offer HPA. Find out what they offer, and choose your system accordingly. Otherwise you will have to find a place to refill.
• There isn't much difference between tank models. The larger the tank, the more CO2 you can put in and the more shots per fill. Some have valves, some have gauges, some have an anti-siphon valve built in.
• A 12 - 16 ounce CO2 tank might be the best size for paintballing, because it is not too heavy, not too light, and holds enough CO2 to last for a game. A 68/3,000 or 68/4,500 fiberwrapped tank from Crossfire is well balanced, and might be the best choice for HPA.

Recommended Sources

All the products reviewed on this site are available from one or more of the following:

They handle a lot of good equitment; its worth taking a look.

Paintball Guns at
Find a large selection to choose from at

Online Sports
The oldest and largest sports catalog on the internet, a large selection to choose from. Use their search box; enter "paintball gun", "paintball hopper", or whatever you are looking for.


Online Sports - Paintball Tanks
Aluminum and carbon fiber.

Related Articles

Paintball Air System Parts
In addition to your tank, you may need a regulator, expansion chamber, anti-siphon tube, drop forward, hose, valves, and connectors.

How to Remove Your CO2 Cannister Safely
Don't remove the valve when you are removing the CO2 from your gun, otherwise you will turn it into a deadly projectile.


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