The hollowbase WC has thin skirts on the hollowbase, and using hotter loads risks blowing out the skirt, ruining accuracy and risking a bore obstruction. They are designed to provide excellent accuracy out to the 50 yd limit of competition bullseye shooting.

The solid BB have no such risk of the base blowing out, and some (many?) shooters prefer a load that kicks as much as 158 grain service ammunition to stay in practice for service revolver competition.