ORIGINAL: deke12ga
ORIGINAL: outdoorsmen
the ribs are for filling the gap between the slug and the barrel due to various bore diameters among manufactures as well as choke sizes. the ribs do not invoke spin on the projectile.
Then why do they call them "rifled slugs" and why are the ribs slanted?
Deke, Outdoorsman is right! Those ribs are there justfor laughs!! "Rifled" slugs have been photographed in flight. Little if any, spin resulted from that "rifling" swaged onto the slugs. Actually, slugs cast in a Lyman mould (smooth sides) shot just as well as the "rifled" ones.
At one time, Lyman sold a swaging die for swaging "lands & grooves" onto slugs cast in their moulds. But when after extensive testing they discovered that "unswaged" slugs shot as well as the ones with the lands & grooves, they quit making the swaging die.....
The ribs aren't even needed to go thru a choke-except for on the Brenneke slugs. Then the ribs are needed, because the slug has a solid body.