18.5mm Flechette Shell
The InstellArms flechette shell is designed to extend the effective range of the shotgun while maintaining high lethality and high probability of a hit. The round consists of 40 500mg steel fin stabilized flechettes, half facing forward and half facing rearward. On firing, the rearward facing flechettes yaw until they are facing forward, forcing the pattern of darts to expand.
The flechettes are able to penetrate a stell helmet or aramid vest at up to 500m, but lack the energy to do significant tissue damage beyond 300m. This performance is deemed acceptable, as most small arms combat occurs at less that 300 meters.
This round is economical to produce, and is manufacturer in great numbers. Use is often restricted to police and military due to its ability to penetrate body armor.