The ornamental design for a firearmmagazine, as shown and described.
FIG. 1 is a perspective view of the firearm magazine of the present invention;
FIG. 2 is a back view of the firearm magazine of FIG. 1;
FIG. 3 is a front view of the firearm magazine of FIG. 1;
FIG. 4 is a right side view of the firearm magazine of FIG. 1;
FIG. 5 is a left side view of the firearm magazine of FIG. 1;
FIG. 6 is a bottom view of the firearm magazine of FIG. 1;
FIG. 7 is a top view of the firearm magazine of FIG. 1; and,
FIG. 8 is another right side view of the firearm magazine of FIG. 1.
The broken line showing of FIGS. 1 through 5 is included for the purpose of illustrating portions of the ammunition magazine that form no part of the claimed design.