Upcut spiral bits are still designd to cut with the sides, as in grooving or morticing. Most do end cut, or drill, to some degree as well but they are not drills. You need to make sure they are designated as center cutting (almost all 1/4 inch do cut to center). The problem is that to keep the tool strong enough to not snap off when side loading, the center web must be left thicker than a drilling tool needs to be. Indeed, in a drilling tool, you need a thinner web so that the chips can evacuate up the flutes freely. Most 1/4 inch upcuts are essentially 1/4 endmills that are virtually undistinguishable from metalcutting forms. They are designed to plunge a little and then side cut, plunge a little more and side cut a little more, making extra room for the chips to escape.
If you use an upcut and experience chip clogging, just peck the hole a bit, like halfway, clear chips by lifting out and plunge again. For shelf pin holes it is probably not necessary to do this but this technique will eliminate burning if you are getting.
