The ornamental design for a hand-operated spray gun for dry-ice blasting device, as shown and described.
FIG. 1 is a front, top and left side perspective view showing the design;
FIG. 2 is a front, top and right side perspective view showing the design;
FIG. 3 is a front elevational view of the design;
FIG. 4 is a rear elevational view of the design;
FIG. 5 is a left side elevational view of the design;
FIG. 6 is a right side elevational view of the design;
FIG. 7 is a top plan view of the design; and,
FIG. 8 is a bottom plan view of the design, wherein the broken line showing of a circle is for the purpose of illustrating an opening and forms no part of the claimed design.