Details[edit | edit source]
The cartridge is of a telescoped configuration, which means that the projectile is embedded within the casing and surrounded by the propellant. The projectile is a 9.85 grain (0.638 grams), fin-stabilized steel flechette encased in a four-part plastic spindle sabot. The cartridge has a side-initiating peripheral primer in an aluminum ring, and the casing is made of polymer. The use of this lightweight material made the cartridge weigh in at around 5 grams, less than half as much as the standard 5.56×45mm NATO round. When fired, the flechette would ride the sabot until it leaves the ACR's barrel, at which point the pieces of the sabot would disperse.
Tests had shown that because of the flechette's flatter trajectory, lower recoil, and lighter weight compared to the standard M855 projectile, it outperformed the M855 with its higher flight speed when zeroed in at 600 meters.
Drawbacks[edit | edit source]
There are drawbacks, however. When the sabot leaves the barrel and disperses, the pieces would be a potential safety hazard to friendly troops or the shooter, bouncing off the ground when firing in prone.
Along with that, due to inconsistencies in the strength of the plastic casings, which deformed from external forces, the flechette tends to leave the cartridge at varying pressures. This, in turn, leads to varying muzzle velocities and changes in trajectory from shot to shot, negatively affecting accuracy. Steyr responded to this problem by experimenting with different materials and combinations of methods.
Another problem lays in the high production costs of these cartridges, meaning that very few countries are interested. In addition to this, is that even though spent casings eject from the bottomside of the ACR, the hot plastic can potentially burn the shooter in the wrists, so they would have to wear gloves to protect their wrists.
See also[edit | edit source]
External Links[edit | edit source]
- cartridgecollector.net page on the 5.56×45mm SCF
- patronensammler.de patrone des monats (German)
- Municion.org page on the 5.56×45mm SCF (Spanish)
- Forgotten Weapons Video: Steyr ACR: A Polymer Flechette-Firing Bullpup From the 90s