The ornamental design for a caulkinggun, as shown and described.
FIG. 1 is a front perspective view of a caulking gun in accordance with our new design;
FIG. 2 is a rear perspective view of the caulking gun in accordance with our new design;
FIG. 3 is a front elevational view of the caulking gun in accordance with our new design;
FIG. 4 is a rear elevational view of the caulking gun in accordance with our new design;
FIG. 5 is a top plan view of the caulking gun in accordance with our new design;
FIG. 6 is a bottom plan view of the caulking gun in accordance with our new design;
FIG. 7 is a right side elevational view of the caulking gun in accordance with our new design;
FIG. 8 is a left side elevational view of the caulking gun in accordance with our new design; and,
FIG. 9 is a front perspective view of the caulking gun in accordance with our new design illustrating a state in which an attachment is attached to the caulking gun.
The broken line showing is for the purpose of illustrating portions of the article that form no part of the claimed design.