Steyr ACR

The Steyr ACR is an Austrian bullpup flechette rifle designed by Ulrich Zedrosser at Steyr Mannlicher in 1987 as an entrant in the United States Army's Advanced Combat Rifle program of 1989 and 1990. In place of a conventional bolt, it used a vertically sliding chamber to fire saboted carbon steel flechette rounds from lightweight polymer telescoped cases, half the weight of standard NATO ammunition, at a muzzle velocity of 4,757 feet per second from a 24 round translucent magazine. It performed well in testing but was never adopted, since none of the program's entrants achieved the required 100 percent improvement over the M16A2, and testers also found inconsistent case strength and a safety hazard from high speed discharged sabots. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/