A pneumatic gun sized and designed to appear like and operate in a manner similar to a conventional handgun. The gun may include a removable magazine storing projectiles and propellant. The entire magazine may be small enough to fit into a handle of the gun (e.g., with a pistol grip). The magazine may be integrated with propellant and projectile portions locked together or separable. Standard carbon dioxide cartridges fit within the magazine. Projectiles may be staggered to increase the maximum magazine load. A user may selectively release just the projectile portion of the magazine, in order to leave the propellant undisturbed until fully expended. The magazine may be completely removed from the gun without substantial loss of propellant.