Most of the cities in AZ categorize airsoft guns/air guns under Firearms, due to that they use expanding gas to propel a projectile, Treat them as you would real fire-arms. But being that they are identified as fire-arms in some locales/situations, they may fall under statutes that apply to real firearms.
AZ law states that an object is considered a firearm when it uses an explosion to propel a projectile. I researched it when I was building my AT-4. So Airsoft guns are not technically considered a firearm in AZ. But if you were to build a potato gun or something similar that uses an explosion, that IS considered a firearm, and is illegal to manufacture and/or use with out proper registration.
Airsoft guns do NOT use explosions. AEG's do not use expanding gas either. Gas guns do use expanding gas, but still no explosions.
So Airsoft Rifles are NOT firearms, but depending on where your at, they can still have the same laws as firearms.
Rule of thumb = TREAT YOUR AIRSOFT RIFLE AS A REAL RIFLE WHEN IN PUBLIC!
NEVER let it be seen by the public, always have it in a case. Even in a case, it would not be a good idea to just go walking down the street with a gun case strapped to your back.
If your not sure, DON'T DO IT!