Okla. Stat. tit. 21, § 1289.4

DEFINITIONS FOR FIREARMS ACT "Rifles" as used in the Oklahoma Firearms Act of 1971, Sections 1289.1 through 1289.17 of this title, shall mean any firearm capable of discharging a projectile composed of any material which may reasonably be expected to be able to cause lethal injury, with a barrel or barrels more than sixteen (16) inches in length, and using either gunpowder, gas or any means of rocket propulsion, but not to include archery equipment, flare guns or underwater fishing guns. In addition, any rifle capable of firing "shot" but primarily designed to fire single projectiles will be regarded as a "rifle".