Drum magazine for a firearm

FIG. 1 is a front, top, left perspective view of a drum magazine for a firearm showing our new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a left side elevation view thereof;

FIG. 5 is a right side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines showing portions of the design in all figures are included for the purpose of illustrating environment and unclaimed features and form no part of the claimed design.