Gas rifles are popular. Google WETTTI AWSS, or WA GBBR, or Tanio Koba GBBR, or GHK Ak, or Daytona Gun ... for all of the modern gas gun systems.
Also, gas rifles are much older... I have less experience, but an example is the Escort gas system.
AEG's are more reliable in the colder weather, and are technically less expensive due to the cost of magazines and propane.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.