Full-bore slugs Shotgun slug

a 12 gauge brenneke slug

the brenneke slug developed german gun , ammunition designer wilhelm brenneke (1865–1951) in 1898. original brenneke slug solid lead slug ribs cast onto outside, rifled foster slug. there plastic, felt or cellulose fiber wad attached base remains attached after firing. wad serves both gas seal , form of drag stabilization. ribs impart small amount of rotation projectile travels down bore. rotation not impart gyroscopic stabilization, rather improves accuracy correcting manufacturing irregularities. additionally, ribs decrease contact surface bore, reducing friction , increasing velocity. ribs deform through choke more readily solid slug would, reducing pressure , wear on choke safe levels.

since brenneke slug solid, rather hollow foster slug, brenneke deform less on impact , provide deeper penetration (see terminal ballistics). sharp shoulder , flat front of brenneke (similar in dimensions wadcutter bullet) mean external ballistics restrict short-range use, accuracy similar of american foster slug while retaining improved penetration , slug integrity of brenneke design.

foster slugs

a foster slug, invented karl m. foster in 1931, , patented in 1947 (u.s. patent 2,414,863) type of shotgun slug designed fired through smoothbore shotgun barrel. designed enable deer hunting in great depression using smoothbore, choked shotguns. foster cast them hand soft lead, filed grooves on exteriors, , sold them neighbors improve hunting potential feed families. foster standard american domestic shotgun slug; referred american slugs differentiate them standard european slug design popularized earlier brenneke. sportswriters have consistently referred these slugs forster slugs, conflating name forster brothers manufactured reloading tools during same time frame, forster slug alternate spelling commonly seen in popular press of 1930s describing these slugs.

the defining characteristic of foster slug deep hollow in rear, places center of mass near front tip of slug, shuttlecock or pellet airgun. if slug begins yaw in flight, drag tend push lightweight rear of slug straight flight, stabilizing slug. gives foster slug stability , allows accurate shooting through smoothbore barrels out ranges of 75 yards (69 m).

most foster slugs have rifling , consists of ribs on outside of slug. brenneke, these ribs impart rotation on slug correct manufacturing irregularities, improving precision (i.e., group size.) unlike traditional rifling, rotation of slug imparts no significant gyroscopic stabilization. ribs minimize friction on both barrel , projectile , allow slug swaged down safely when fired through choke, although accuracy suffer , choke wear may progressively accelerated when fired through gauge choked tighter improved cylinder. foster slugs can safely swaged down more brenneke slugs, when fired through choke, being hollow. amount of wear on choke therefore less of problem when shooting brenneke slugs. safe fire foster slugs through rifled slug barrels.

roll-crimping traditionally used close shotgun shell containing foster slug. increases difficulty handloading foster slugs. during 1930s, though, many if not shotgun shells roll-crimped on overshot card, , hand tools putting roll crimp on paper shell readily available , inexpensive.