Using The Umarex Gauntlet With CO2 Power – Part One
Most PCP air rifles can only use High Pressure Air as their power supply. But one is different. You can use the Umarex Gauntlet with CO2 power.
This gives a great alternative for those airgunners who want to shoot the Gauntlet but don’t have their own large HPA tank, or want to use a hand pump.
Shooting Umarex Gauntlet with CO2 power can be a cheap and convenient solution as CO2 is available almost everywhere.
In this article, we’ll explore how to use the Umarex Gauntlet with CO2 power and the multiple ways in which you can do so. But first a note of caution:
IMPORTANT SAFETY NOTE: If you want to use Umarex Gauntlet with CO2 power, you need to buy a separate 9-Ounce CO2 paintball tank. Do NOT fill the regulated HPA tank supplied with Gauntlet with CO2. Also, CO2 paintball tanks must NEVER be filled with High Pressure Air as they can’t take the pressure.
The regulated HPA action pressure of Gauntlet – 1,150 PSI in the .177 and .22 caliber versions – is about the same as the maximum pressure of CO2. It’s this unusually low action pressure that allows Gauntlet unparalleled versatility in filling.
Unlike a few other PCP air rifles that can also work with CO2 power, no other changes or adjustments are required to use the Umarex Gauntlet with CO2 power.
First, remove the shroud from around the regulated HPA tank. Completely unscrew the front sling stud and remove it. Push in the two tabs at the sides of the shroud. The shroud can now be pulled forward, free from the rear part of the buttstock.
This gives you complete access to the regulated HPA tank.
Now degas the Gauntlet. Unscrew the regulated HPA tank to remove from the gun.
Above is the Gauntlet’s de-gassing key. Below we see it in use.
Attach the CO2 source, with an adapter if necessary. You’re immediately ready to shoot the Umarex Gauntlet with CO2 power!
You’ll probably want to leave the tank shroud uninstalled when using CO2 for ease of changing tanks. It’s not pretty, but it’s practical!
Appreciate the benefits of CO2.
But why would you possibly want to fill your beautiful, new High Pressure Air Umarex Gauntlet with CO2 power?
In a word: convenience. Well, actually three words: convenience and cost.
For some shooters, pumping with a hand pump is not a viable option and there’s no convenient local source of High Pressure Air. The nearest paintball store or dive shop could be hour’s drive away.
But CO2 supplies are as close as your nearest Walmart, or big box sporting goods retailer. CO2 is cheap and, best of all, it requires no expensive filling equipment. CO2 will work just fine in Gauntlet, but it has different properties as a propulsive gas from HPA. Let’s take a few minutes to understand these differences.
Firstly, you get more shots from a set volume of CO2 than you do from High Pressure Air. But those shots are usually slower. (Why usually? We’ll explain below).
Secondly, and unlike High Pressure Air, CO2 varies in pressure quite dramatically with temperature. CO2 is also a refrigerant gas – every time you pull the trigger on Gauntlet (or any other CO2-powered gun) – you cool it, making the next shot slower.
There’s a connection between these two things. For complex reasons that we don’t need to cover here, CO2 in a tank has a maximum possible pressure of 1,100 PSI. This pressure is achieved with the gun – and the CO2 in its tank – at around 95 degrees F, or thereabouts. This means that, if you shoot Gauntlet at 95 degrees F, it will shoot at approximately the same FPS as if the gun were using HPA.
But, when you shoot the Umarex Gauntlet with CO2 power at lower temperatures, the muzzle velocity falls away. This is because the CO2 pressure in the tank drops as the temperature falls. In fact, the drop is approximately 2 FPS per degree F.
Lower pressure means lower muzzle velocity. So, if your Gauntlet is shooting on CO2 at, say, 800 FPS at 95 degrees F, the same gun with the same pellets will shoot at around 740 PFS at 65 degrees F.
As it’s not unknown for the tanks of CO2 guns to actually become covered in frost if they are fired rapidly, you can imagine what happens to the FPS. It goes through the floor! There is an answer, shoot slower to reduce the temperature drop.
But don’t get too down on the negative aspects of shooting with CO2. CO2 power has a long and honorable history as an airgun propellant and many CO2-powered airguns continue to be introduced today. Remember the positives: cost and convenience.
In the next part of this story, we’ll look at the different CO2 sources you can use to shoot the Umarex Gauntlet with CO2 power.
You’ll find much more detailed information like this about the Gauntlet air rifle in HAM Publisher Stephen Archer’s major book “Choosing and Shooting The Umarex Gauntlet Air Rifle”.