But would it be legal to shoot an air rifle in a suburban yard where houses are close together?
Pretty sure that is something local govt controls, best to ask your local police department or the State Police. That is what I did. But, in NJ just about everything that can eject a projectile is considered a firearm, so be careful where you point your rear end
From
NEW JERSEY ADMINISTRATIVE CODE
TITLE 13. LAW AND PUBLIC SAFETY
CHAPTER 54. FIREARMS AND WEAPONS
"Firearm or firearms" means any handgun, rifle, shotgun, machine gun, assault firearm, automatic or semi-automatic rifle, or any gun, device or instrument in the nature of a weapon from which may be fired or ejected any solid projectile, ball, slug, pellet, missile or bullet, or any gas, vapor or other noxious thing, by means of a cartridge or shell or by the action of an explosive or the igniting of flammable or explosive substances. It shall also include, without limitation, any firearm which is in the nature of an air gun, spring gun or pistol or other weapon of a similar nature in which the propelling force is a spring, elastic band, carbon dioxide, compressed or other gas, or vapor, air or compressed air, or is ignited by compressed air, and ejecting a bullet or missile smaller than three-eighths of an inch in diameter, with sufficient force to injure a person."