ACR Steyr
Summary
| Country | 🇦🇹 Austria |
| Category | Bullpup assault rifle |
| Manufacturer | Steyr |
Technical specifications
| ACR Steyr | |
|---|---|
| Fire Rate | 650 rounds/min. |
| Caliber | 5.6 mm flèchettes |
| Magazine | 30 rounds |
| Length | 750 mm (29.5 in) |
| Weight | 3.23 kg (7.1 lb) |
| Range | 500 m (1640 ft) |
Description
The Steyr ACR was a prototype flechette-firing assault rifle developed for the US Army's Advanced Combat Rifle (ACR) program, which ran from 1989 to 1990. The program concluded without any entrant demonstrating a 100% performance improvement over the M16A2, the established baseline for a successful ACR weapon, even though the Steyr design and most other submissions proved effective during testing.
This bullpup-configured firearm houses a 24-round magazine near the buttstock. While superficially resembling the Steyr AUG, the ACR has a rounder profile and a largely enclosed barrel. The stock splits forward from the magazine well to below the sights, allowing cleaning access. An optical sight was a standard feature. The weapon's cycling system uses a vertically mobile chamber. When fired, propellant gases move the chamber downward, a new round is inserted from the rear, and the spent case ejects forward of the magazine. Springs return the chamber upward into a fixed block where it locks. A fixed firing pin sits above the chamber, contacting the primer ring through a small aperture. The chamber is normally held down, and the trigger initiates the upward movement and firing sequence.
The specialized ammunition features a saboted carbon steel flechette in a telescoped, propellant-filled plastic case, 45 mm long and 10.4 mm in diameter, with an aluminum priming ring at the base. The 0.66 g flechette is about 1.6 mm in diameter and 41.25 mm long, with a roughened surface. The sabot is a four-part spindle type made of liquid crystal polymer. Each cartridge weighs 5.1 g, less than half the weight of 5.56×45mm NATO ammunition.
During the ACR program testing phase, the Steyr ACR performed effectively. Two primary issues were identified:
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Variable strength in the plastic ammunition cases affected ballistic consistency, potentially solvable with material improvements and quality control.
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Discharged sabots retained significant velocity, posing a hazard to nearby personnel or the shooter when firing prone due to ground impact deflection.
The ACR program, for which this prototype was developed, concluded without adopting any system, and the Steyr ACR was not adopted for general service.