Abstract: A drum magazine for loading paintballs and shaped projectiles into a magazine-fed firearm includes a spiral feed track that stores paintballs as well as a projectile feed assembly that pushes paintballs through the spiral feed track. Paintballs exit the spiral feed track through a feed port and through a modular feed adapter that is inserted into a paintball marker. A clock spring and a spring rotor are utilized in order to adjust the pressure that is exerted on paintballs within the spiral feed track. Tension in the clock spring may be increased to a desired level by rotating the spring rotor to wind the clock spring. Paintballs are prevented from loading when the drum magazine is not loaded into a paintball marker by a locking assembly. A ratcheting gear engages a gear locking pawl while the drum magazine is not loaded, preventing the clock spring from becoming unwound.