Abstract: A spring for a firearm magazine includes a top attachment leg, a plurality of upper coils connected to the top attachment leg, a plurality of intermediate coils below the upper coils, and a bottom attachment leg below the plurality of intermediate coils. The upper coils are sized and shaped to nest within the intermediate coils when the spring is fully compressed, reducing the solid height of the spring. In some embodiments, at least two complete upper coils and/or at least two complete lower coils nest within intermediate coils. In one example, at least some coils have a rectangular coil shape. The spring can be configured for use in a handgun magazine or a rifle magazine, for example. A handgun magazine and a magazine components kit including the spring are also disclosed.