## Wednesday, May 25, 2005

### Warm weather means hotter velocities for CO2 guns!

By B.B. Pelletier

Shooters in Florida, the Southwest and Hawaii don't worry much about cold weather, but the rest of us do because the winter puts an end to outdoor shooting with CO2 guns. Now that summer is back in almost every corner of the US, all of us can head outside again for loads of powerful CO2 shooting!

Many of you may already know that warm ambient temperatures can increase velocity in a CO2 gun. How? Because CO2 evaporates at higher pressures as the air temperature increases. As the air temperature increases, CO2 is warmed and more pressure is achieved inside the CO2 container. And, as you know, higher pressure means more power!

Did you know that barrel length also increases velocity? Let's take a look at a CO2 pistol that demonstrates this perfectly.

How to get an extra 110 f.p.s. from a pistol
The velocity for a .177 TAU 7 Match pistol is 450 f.p.s. The same gun with an extra two inches of barrel - the TAU 7 Silhouette - gets 560 f.p.s. It's amazing that just adding length to this barrel - with no other functional changes in the gun - will make a pellet go 110 f.p.s. faster!

A longer barrel means compressed gas has more time to accelerate a projectile because the released gas is escaping in an enclosed environment - between its source and the pellet. Because it is captive, the gas is channeled into moving the pellet forward. Once a pellet leaves the barrel, it immediately starts to slow down. Since the gas is pushing the pellet for a longer period of time (an extra two inches, in the case of our TAU pistol), it is giving it that much more speed. So, you can choose between higher gas pressure (when temperatures are warmer) or a longer barrel to increase velocity in your CO2 gun. What if you combined these two? You'd extract the maximum velocity from your gun!

Another trick to get the most velocity from your CO2 gun
To get even more velocity from your CO2 guns, simply pause for a longer time between shots - at least 30 seconds is good in cooler weather. In the hot summer with the sun shining, a pause of 10-15 seconds is all it takes. The gun cools down with the shot because CO2 acts as a coolant. By allowing it to warm up again, you'll gain extra power.

Warm weather safety for CO2 guns
There is a limit to how hot a CO2 gun or container should get! If you leave a gas gun or container in a closed car on a summer day, it can explode! At the very least, it will blow the seals out of the gun; at the worst, it could remove your windshield or even injure somebody. CO2 containers not enclosed in the gun could also explode. Be very attentive whenever a gas gun is exposed to temperatures above 80 degrees F. If that means exhausting the gas from the gun or the container, then do it. That’s better than an accident.

At May 28, 2005 2:27 PM,  Anonymous said...

I have a daisy powerline 990 it is co 2 and pump

is this a good gun for summer and winter?

I couldn't find your post on co2 and pcp. I haven't seen any other rifles like this one.

At May 29, 2005 7:53 AM,  B.B. Pelletier said...

Your 990 should be good year-round. If the weather gets too cold to use gas, simply switch to air and keep on shooting.

I'm also unaware of any other guns that use both gas and air, except some Quackenbush Brigands (a .375 big bore) can be filled with either CO2 or gas, but the air has to be kept to 1,200 psi to allow the valve to open.

B.B.

At January 22, 2006 2:41 AM,  Anonymous said...

I want to get another gun and I want to know which gun is better, an co2 owered gun, a spring gun, or an air gun? I want a strong gun that is powerful enuff to break through skin and thick glass.

At March 26, 2008 6:08 PM,  mfcstevenson said...

B.B,

Did you not completely contradict yourself wit this post from the last post about barrel length?

a fan.

At March 27, 2008 6:07 AM,  B.B. Pelletier said...

mfcstevenson,

I don't know the statements you are referring to. If you will please direct me to the places I made them, and what, exactly, you are talking about, I can comment.

B.B.

At March 27, 2008 6:54 AM,  mfcstevenson said...

My apologies. I got it confused. I read your post on barrel length and how you say it does not affect accuracy, and then read this post on CO2 and how barrel length affects power on a CO2 and got it confused! Don't worry I was just being a bit pedantic. Sorry again.

At March 27, 2008 7:45 AM,  B.B. Pelletier said...

mfcstevenson,

I wasn't snapping at you; I just didn't understand your question. Written exchanges can sometimes sound harsher, because they lack inflection and body language.

As for barrel length affecting velocity for CO2, it does to a point, but that point is reached much sooner than with a pneumatic. For a smallbore caliber like .177 or .22, as little as 14-15 inches may be the optimum length, depending on the valve.

B.B.