placing more mass in the front of the projectile, therefore inhibiting the "tumble" that normal slugs may generate. The Brenneke slug takes this concept a bit further, with the addition of a wad that stays connected to the projectile after discharge, increasing accuracy. Both slugs are commonly found with fins or ribs, which are meant to allow the projectile to safely squeeze down during passage through chokes, but they do not increase stability in flight. Flechette rounds contain aerodynamic darts, typically from 8 to 20 in number. The flechettes provide greatly extended range due to their aerodynamic shape and improved penetration of light armor. American troops during the Vietnam War packed their own flechette shotgun rounds, called beehive rounds after the similar artillery rounds. However, terminal performance was poor due to the very light weight of the flechettes, and their use was quickly dropped. Grenade rounds use exploding projectiles to increase long range lethality. These are currently experimental, but the British FRAG-12, which comes in High Explosive (HE), High Explosive Armor-piercing (HEAP) and High Explosive Fragmenting Antipersonnel (HEFA) forms, is under consideration by military forces. Less-lethal rounds, for riot and animal control Flexible baton rounds, commonly called bean bags, fire a fabric bag filled with birdshot or a similar loose, dense substance. The "punch" effect of the bag is useful for knocking down targets; the rounds are used by police to subdue violent suspects. The bean bag round is by far the most common less-lethal round used. Due to the large surface area of these rounds, they lose velocity rapidly, and must be used at fairly short ranges to be effective, though use at extremely short ranges, under , can result in broken bones or other serious or lethal injuries. The rounds can also fly in a frisbee-like fashion and cut the person or animal being fired at. For this reason, these types of rounds are referred to as less-lethal, as opposed to less-than-lethal. Gas shells spray a cone of gas for several meters. These are primarily used by riot police. They normally contain pepper gas or tear gas. Other variations launch a gas-grenade-like projectile. Rock salt shells are hand loaded with coarse rock salt crystals, replacing the standard lead or steel shot. Rock salt shells could be seen as the forerunners of modern less-lethal rounds. In the United States, rock salt shells were and are sometimes still used by