Airsoft Canada - Blowback?

http://wiki.airsoftcommunity.co.uk/Gas_Blowback

Quote:

GAS blowback refers to a type of gun, usually a pistol or sub machine gun, that uses gas to cycle and fire BBs in a realistic fashion. The term 'blowback' refers to the slide moving rapidly backwards after each shot. This motion cocks the hammer and allows the next round to be raised to the top of the magazine. A spring then pushes the slide forwards to its normal position, the raised round is moved forward into the chamber, and the gun is ready to be fired again.

Due to the realistic cycling of the slide, and the slight kick or recoil that is felt during each shot, GBB guns are widely held to be the most fun type of airsoft gun to shoot. However it should be noted that because a portion of the energy is used in the movement of the slide, GBB weapons tend to have a slightly reduced power compared to NBB weapons. The drop in power due to cold conditions is also more notable in GBB weapon than NBB, meaning that they tend to be less reliable in wildly varying conditions.

Temperature limits

A series of relatively unscientific tests were conducted to assess the lowest temperature at which a GBB would function. The temperature was measured using a digital thermometer equipped with a k-type thermocouple, and the measurement point was the recess in the side of the magazine which engages with the magazine retention catch in the handgrip. The magazine capacity was 24 rounds. For each measurement, the magazine was filled using a speed loader and topped up with green gas. The magazine was emptied at about 1.5 shots per second. The test was conducted indoors in an ambient temperature of about 20 degrees Celsius.

It was found that the magazine cooled by nearly 5 degrees each time it was rapidly emptied. When it had reached 2 degrees Celsuis, power had already dropped significantly. On refilling and regassing, the slide failed to cycle after only a few more rounds. The temperature was taken and found to be -2 degrees Celsius. One may conclude from this that a GBB gun is very unlikely to function in sub-zero temperatures, and may be marginal at temperatures below about 5 degrees.