How does cold weather affect different airgun powerplants?
By B.B. Pelletier
Today's topic was suggested by a reader who asked, "How are PCPs affected by the cold?" That's a good question for every type of airgun powerplant, so I included all of them in today's post.
CO2 is a "no go" in the cold
Most airgunners already know this, but I'm covering all the bases. Because the pressure of carbon dioxide gas depends on the temperature, a CO2 gun starts performing poorly below 40 degrees F. It remains gaseous to a much lower temperature, but it lacks the required pressure for use as an airgun propellant at those lower temperatures.
Another thing about CO2 guns is that they cool themselves as they fire. It doesn't even take a 40-degree day to freeze up a gun. You can actually freeze the operating parts of a CO2 gun on a 90-degree day if you shoot it fast enough. That's why the Drozd submachine gun has burst-fire rather than full-auto, which would freeze the mechanism.
Guns with steel springs are the next most affected!
Surprise! You probably thought spring guns with coiled steel mainsprings were impervious to the cold, but that's not the case. The lubricant inside the powerplant - mostly on the mainspring - is the culprit. When the temperature drops down around zero, these springers start exhibiting a loss of velocity that escalates quickly as the temperature drops.
Gas springs are better, but not perfect
I actually tested the velocity of a steel spring and gas spring gun at 50 degrees and zero degrees F. The steel spring gun lost 50 f.p.s. at zero degrees. The gas spring lost perhaps 5 f.p.s., which is negligible. A gas spring gun also has some lubrication in the powerplant, but the real culprit for loss of velocity is the decline in pressure inside the gas spring unit. So, if you want to hunt in cold weather with a spring rifle, choose the Beeman RX-2.
Precharged guns and other pneumatics are the champs!
For cold weather operation, the PCP or other pneumatic airgun is the clear winner. I put the PCP ahead of the multi-pump and single-stroke pneumatic because when the pump seals get cold and stiff, it takes some work to warm them up so they're flexible again. That might not be a problem in Tennessee - but in Minnesota or Alaska it can be.
A PCP, however, looses virtually no velocity at zero degrees. They might, if you shoot guns with steel breeches and hammers oiled with petroleum-based lubricants such as the Logun S-16. I haven't tested many of these at low temperature, but the lubrication of the action parts could cause some slowdown.
The Talon SS from AirForce is primarily made from synthetic and aluminum, and the lubes are either dry film or part of the materials, themselves. It makes heavy use of Delrin, a Dupont engineering plastic with excellent low-temperature lubricity. The Talon SS I tested had no loss of velocity down to 20 degrees below zero (I tested it on a separate day and was unable to get another to re-test the two springers or another PCP). It was the best low-temp airgun I tested.
That's it for cold-weather operations. We'll look at heat, wind and rain next.