CO2 always better than Gas Gas is a less stable technology in changing climates, although CO2 guns have always had the same problem: too much power. However, SECUTOR has worked intensively on their O-rings, which enable their guns to offer stable 300-305 FPS with 0.20 g BBs using CO2 (bearing in mind the ideal power for European CQB). We were able to test the first batch in Taiwan and later in our offices. Always stable at that power, it's no coincidence! When manufacturing, do it right. The recoil spring rail is made of cast iron, and so are several of the internal parts. Other items such as the trigger or the hammer are made of aluminium, and special care has been taken in manufacturing the casing of the barrel (the front piece that holds the barrel centered in the slide) which is the part of the gun that suffers most. The mould of this piece has been modified (many models were inspired by the Japanese Marui system) to provide more resistance to the powerful blowback. Go ahead and grab one, cock it, release it and listen to the amazing metallic sound.