How to Pick Good Quality CO2

Why it is very important to use good quality CO2 in your CO2 powered airguns.

Many of the air pistols and T4E (RAM) markers serviced at our gun benches involve inoperable and clogged valves or deteriorated o-rings and seals. More times than not, its evident that a lesser quality CO2 cylinder was regularly used in these airguns and markers. The performance life of your CO2 gun’s valve and seals depends heavily on the cleanliness of the CO2 you’re using as well as the type of seal the cylinder creates against your airgun’s o-ring. Dirty CO2 can also cause diminished velocities and equate to fewer shots per cylinder.

There are several brands of CO2 capsules to choose from and without being able to see inside of each capsule, it is impossible to know which brand or brands offer the cleanest CO2 and are of the best quality. CO2 cartridges also come from various manufacturers and countries, all of which have differing standards of quality control. Each capsule has to conform to size, weight and temperature threshold specifications, but there are no regulations governing the cleanliness of the CO2 or the capsule, so it is hard to know which is the best without testing each and every one—you could go through several o-rings and destroy a valve or two before figuring out which is best.

Because of the number of “bad” seals and valves we were seeing, we cut open some Walther/Umarex CO2 capsules and some leading branded CO2 capsules. We were amazed at the difference.

The leading brand had extraordinary amounts of oil and grit lining the walls of the capsule. The Umarex/Walther CO2 capsule was absolutely clean. The color, texture, and smell of the grime in the leading brand cylinder was consistent with what we were seeing on our gunsmith bench and is what we determined to be the main cause of most of the “bad” o-rings and valves we were seeing in the airguns coming in for service.

Use Good Quality CO23

Another issue we often have calls about is CO2 leaks. The most common leak is caused by a CO2 cartridge’s tip making a bad seal against an o-ring. CO2 cartridges are filled with liquid CO2 and then capped. There are at least three different styles of caps and one may work better than another in your CO2 gun. Take a close look at the valve where your CO2 cartridge fits into the airgun. If the cartridge simply presses against a seal, most of the time any of the three will work. If your cartridge slides through an O-ring, you could experience leaks if you use the wrong kind of cylinder. Take a look at the three CO2 cylinders in the picture. The cylinder on the left is totally crimped on. The one in the middle has a pressed on top that leaves a groove around the neck and the one on the right has a smooth neck. If your airgun has a slide-through o-ring, the style on the right is the only style of these three you should use. Umarex/Walther CO2 cylinders are produced in this fashion and the only kind we use in our airgun testing facility.

Umarex CO2You will also notice in the picture that the dimensions of the neck and shoulder of the capsules vary. We see many instances where leading brand capsules (the first and second capsules from left) will not fit properly into an air pistol and then will not pierce correctly due to incorrect dimensions. Do not apply excessive force or use pliers to get these ill-shaped capsules in your airgun. Doing so could damage the gun’s frame and/or puncture assembly.

One final tip to consider, and the easiest to do, always put a drop of RWS Chamber Lube or other airgun valve oil on the tip of each CO2 capsule before installing it. Doing this will extend the life of your valves and o-rings and can prevent leaks. This one simple tip alone could save you a service call.

Tested and proven clean CO2 cylinders with the “good” type of O-ring, to extend the life of your gun: