I claim the ornamental design for an octagonal sided under hammer style action, as shown and described.
FIG. 1 is a perspective view of an octagonal sided under hammer style action, showing my new design;
FIG. 2 is a front elevational view of the invention;
FIG. 3 is a rear elevational view of the invention;
FIG. 4 is a left-side elevational view of the invention, the right-side elevational view being a mirror image thereof;
FIG. 5 is a top plan view of the invention; and,
FIG. 6 is a bottom plan view of the invention.
Portions of the design shown in broken lines in FIGS. 1–5 are included for the purpose of illustrating environment and form no part of the claimed design.