Side-loading fixed magazine with retractable follower and sliding ammunition loading sleeve

An affixable ammunition magazine configured for use with a firearm with an upper receiver and a lower receiver, the receivers configured to be disengaged and re-engaged, the lower receiver having a magazine well for receiving the ammunition magazine, the ammunition magazine comprising:

• a magazine body configured to contain a stack of cartridges, the magazine body having a feeding end configured to feed rounds of ammunition to the firearm, the magazine body including a rear opening;
• a movable sleeve configured to surround the magazine body and secure the stack of cartridges, the movable sleeve having at least one sleeve groove along at least one side, the at least one sleeve groove having a groove end catch;
• a cartridge follower assembly having:
• a cartridge follower, and
• a cartridge follower spring configured to be compressed by the cartridge follower when the groove end catch has engaged with and has pulled down the cartridge follower, and the cartridge follower spring is configured to expand when the groove end catch is disengaged from the cartridge follower, thereby allowing the cartridge follower to urge the stack of cartridges towards the feeding end of the magazine body;
• and
• an attachable blocking tab configured to be attached to the feeding end of the magazine body, and configured to block removal of the ammunition magazine from the magazine well, the attachable blocking tab being attached to the feeding end of the magazine body after insertion of the ammunition magazine into the magazine well, and before re-engaging the upper receiver with the lower receiver.

An affixable ammunition magazine configured for use with a firearm with an upper receiver and a lower receiver, the receivers configured to be disengaged and re-engaged, the lower receiver having a magazine well for receiving the ammunition magazine, the ammunition magazine comprising:

• a magazine body configured to contain a stack of cartridges, the magazine body having a feeding end configured to feed rounds of ammunition to the firearm, the magazine body including a front opening;
• a movable sleeve configured to surround the magazine body and secure the stack of cartridges, the movable sleeve having at least one sleeve groove along at least one side, the at least one sleeve groove having a groove end catch;
• a cartridge follower assembly having:
• a cartridge follower, and
• a cartridge follower spring configured to be compressed by the cartridge follower when the groove end catch has engaged with and has pulled down the cartridge follower, and the cartridge follower spring is configured to expand when the groove end catch is disengaged from the cartridge follower, thereby allowing the cartridge follower to urge the stack of cartridges towards the feeding end of the magazine body;
• and
• an attachable blocking tab configured to be attached to the feeding end of the magazine body, and configured to block removal of the ammunition magazine from the magazine well, the attachable blocking tab being attached to the feeding end of the magazine body after insertion of the ammunition magazine into the magazine well, and before re-engaging the upper receiver with the lower receiver.