I have read conflicting reports that slugs work as well or better than pellets with head shots, or that they don't have the penetration ability as a pellet does. Now this may be due to caliber. Possibly a large hollow point at the nose of the slug while great for expansion, not to good for thicker skull. Body shots are undisputed. My curiosity is with limits due to caliber and hollow point size. Obviously a 177 at a large pig is not recommended , just as a 65g slug at 900 FPS is not intended for a chipmunk! LOL! Seriously though, what kind of penetration results have you attained with slugs versus pellet counterparts? I would conduct these tests myself, but I lack a private range.