Okla. Stat. tit. 21, § 1289.3
"Pistols" 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 less than sixteen (16) inches in length, and using either gunpowder, gas or any means of rocket propulsion, but not to include flare guns, underwater fishing guns or blank pistols.
Laws 1971, HB 1248, c. 159, § 3, emerg. eff. May 24, 1971; Amended by Laws 1995, SB 3, c. 272, § 41, eff. September 1, 1995.