The ornamental design for spray gun, as shown and described.
FIG. 1 is a front elevation of spray gun showing my new design, a rear elevation view is a mirror image of the front elevation view thereof;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a left side elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a perspective view of spray gun in a first orientation; and,
FIG. 7 is a perspective view of spray gun in a second orientation showing my new design thereof.
The broken line showing contour of the circular elements of the gun in FIG. 5 is for the purpose of illustrating a portion of the article and forms no part of the claimed design.