Abstract: A magazine for a firearm holds cartridges in three sections: a top section, a middle section and a bottom section. The top section is detachable. The middle section has a smaller width and depth than the bottom section so that the middle section can be inserted into the bottom section of another similarly formed magazine. A removable bottom cover closes the bottom section. A spring with removable segments rests on the bottom cover. A c-shaped member fixed to each spring segment permits adding segments. Two magazines may be combined by removing the top section of a second magazine, detaching the bottom cover of a first magazine, removing a spring segment of the second magazine, connecting the shorter spring to the spring of the first magazine; and slidably inserting the middle section of the second magazine into the bottom section of the first ammunition magazine over the larger spring.