The ornamental design for a triggerguard for a firearm, as shown and described.
FIG. 1 is a right, front, bottom perspective view of a of a trigger guard for a firearm attached to a firearm showing our new design;
FIG. 2 is a right, front, bottom perspective view of the trigger guard for a firearm of FIG. 1;
FIG. 3 is a left side elevation view of the trigger guard for a firearm of FIG. 1, the right side elevation view being a mirror image thereof;
FIG. 4 is a top plan view of the trigger guard for a firearm of FIG. 1;
FIG. 5 is a bottom plan view of the trigger guard for a firearm of FIG. 1;
FIG. 6 is a front elevation view of the trigger guard for a firearm of FIG. 1; and,
FIG. 7 is a rear elevation view of the trigger guard for a firearm of FIG. 1.
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. The long-short segment broken line indicates a boundary line and the unshaded surfaces adjacent the boundary line form no part of the claimed design.