Magazine for pump action shotgun

A magazine for a firearm comprising:

• a housing having a front wall, a rear wall, a top wall, a bottom wall, a left side wall and a right side wall;
• said front wall having an inner surface and said rear wall having an inner surface;
• a tubular drum having an outer surface also has opposite ends that are journaled in said respective inner surfaces;
• an annular chamber is formed in said housing with the inner surface being defined by the outer surface of said tubular drum and the outer surface of said annular chamber being defined by said top wall, said bottom wall, said left side wall and right side wall;
• said housing having a substantially vertical tubular chimney section having a top end, a bottom end, a front wall and a rear wall;
• an outlet port is formed in the top end of said chimney section and an inlet port is formed in the bottom end of said chimney section;
• said tubular chimney section having a linearly extending chamber and its bottom end is in communication with said annular chamber;
• means for spring loading said drum so that the drum will rotate with respect to the front and rear walls of said housing;
• means on the outer surface of said tubular drum for capturing ammunition shells so that they can be carried along said annular chamber toward the inlet port of said chimney section as said drum rotates;
• a shell ammunition follower assembly having a front end and a rear end, said shell ammunition follower assembly travels immediately behind a last round of ammunition and pushes it forwardly toward the outlet port of said chimney section of said magazine;
• means for connecting the rear end of said shell ammunition follower assembly to said rotating drum;
• a shell retainer unit mounted in said chimney section for preventing shells from exiting the outlet port of said chimney section when said magazine is detached from a firearm;
• and
• a feed lip assembly having a front end and a rear end, means for moving said feed lip assembly into and out of a position covering the outlet port of said chimney section.