The debut of rifled shotgun slugs by Foster (United States) and Brenneke (Germany) during the 1930s added reach and accuracy to smoothbore deer guns, relegating buckshot to close running shots. Most notably, “buck” served hunters running whitetails with hounds in Southern thickets. 

The cost of rifled slug loads, however, sparked a home-made alternative. In early paper shotshells an iron cup that reinforced the head, or a varnished metal coil around the powder, reduced the risk of “cut-off” that could happen when the hull got wet. Case separation hiked pressures when the entire front of the shell bulled its way though the forcing cone and choke. Intentional scoring of a paper hull with a pocketknife delivered this result too, but this “cut shell” held the shot together so it flew a short distance as a unit — a slug. Cut shells were economical but not accurate. Given the elevated pressures, they could be hard on guns and, in some, hazardous to fire. During the 1960s, plastic shotshells, shot collars and shot cups all but nixed cut-offs. As better rifled slugs, then sabot slugs in rifled barrels trounced the cut shell ballistically, and heavy loads of plated buckshot in granulated filler gave hunters another option, cut shells faded, mercifully, into history. 

Can big buckshot crowding a tight choke also bump pressures? Ammo makers haven’t cautioned shooters about that. However, the most uniform patterns from tight chokes may come with smaller shot.