A Remington 870 12 gauge with sighted cylinder bore barrel suitable for Foster Slugs and Buckshot.
A Foster slug, invented by Karl M. Foster in 1931, and patented in 1947 (U.S. Patent 2,414,863) is a type of shotgun slug designed to be fired through a smoothboreshotgun barrel. It was designed to enable deer hunting in the Great Depression using smoothbore, choked shotguns. Foster cast them by hand from soft lead, filed grooves on their exteriors, and sold them to his neighbors to improve hunting potential to feed their families. The Foster is the standard American domestic shotgun slug; they are sometimes referred to as "American slugs" to differentiate them from the standard "European slug" design popularized earlier by Brenneke. Some sportswriters have consistently referred to these slugs as a "Forster" slugs, conflating the name with the Forster Brothers who manufactured reloading tools during the same time frame, so "Forster slug" is an alternate spelling that is commonly seen in the popular press of the 1930s for describing these slugs. The defining characteristic of the Foster slug is the deep hollow in the rear, which places the center of mass very near the front tip of the slug, much like a shuttlecock or a pellet from an airgun. If the slug begins to yaw in flight, drag will tend to push the lightweight rear of the slug back into straight flight, stabilizing the slug. This gives the Foster slug stability and allows for accurate shooting through smoothbore barrels out to ranges of about 75 yards (69 m). Most Foster slugs also have "rifling", which consists of ribs on the outside of the slug. Like the Brenneke, these ribs impart a rotation on the slug to correct for manufacturing irregularities, thus improving precision (i.e., group size.) Unlike traditional rifling, the rotation of the slug imparts no significant gyroscopic stabilization. The ribs also minimize the friction on both the barrel and projectile and allow the slug to be swaged down safely when fired through a choke. Foster slugs can safely be swaged down much more than Brenneke slugs, when fired through a choke, being hollow, however recommendations are generally for cylinder bore or improved cylinder chokes. Roll-crimping is traditionally used to close a shotgun shell containing a Foster slug. This increases the difficulty for handloading Foster slugs. During the 1930s, though, many if not most shotgun shells were roll-crimped over an overshot card, and hand tools for putting a roll crimp on a paper shell were readily available and very inexpensive. Edit
Well, I stand corrected!
Where in the heck did I get the idea it was "Forster" instead of "Foster" ?
I'm sure I've seen "Forster" in print for decades... Sigh..