"In theory, Hevi Shot's misshapen pellets shouldn't pattern well at all, yet their high density seem to overcome their eccentric shapes. In fact, early test bunches of Hevi Shot that were sorted and polished for perfect roundness patterned only about 2.5 percent better than the ugly pellets in the production loads."

Philip Bourjaily
Field and Stream

The extra cost would come from the sorting and polishing.