The Anti-Materiél Rifle 5075 (AMR 5075 for short) is a prototype Austrian anti-materiel rifle developed by Steyr Mannlicher.
This massive anti-materiel rifle was the brainchild of Steyr Mannlicher during the mid-1980s when an interest in developing large-caliber heavy sniping rifles was all the rage; Steyr themselves began designing their own heavy sniping rifle, when they envisioned a semi-automatic rifle capable of accurate fire up to 1,000 metres (3,300 feet; 1,100 yards) being able to be manned by a two-man crew, with the intended targets being lightly armored vehicles, armored personnel carriers and the like. However, Steyr concluded that the term "sniping rifle" would give people the wrong impression as to the purpose of these high-caliber rifles; as such, the rifle Steyr would be designing was classified as an anti-materiel rifle.
All of these factors led to the procurement of the AMR 5075, which was manufactured in small numbers for experimental purposes, and was first publicly showcased in 1990. While a great deal of interest was shown, the AMR 5075 was unfortunately, a case of bad timing; it was designed during a time when military spending was declining, and as such, the AMR 5075 failed to get adopted by any military power.
The AMR 5075's design would later be refined by Steyr to become the IWS 2000.
The AMR 5075 uses a long recoil system, i.e. the barrel and bolt recoil together when fired. The barrel and bolt recoil backwards almost 10 inches (25 centimetres) when fired. This system does help to absorb some of the recoil force, though most of the force is absorbed by its prominent high-efficiency multi-barrel muzzle brake. The barrel recoils through what seems to be a sleeve-type hydro-pneumatic recoil system, akin to those found on artillery pieces.
With these measures in place, the AMR 5075's recoil is reduced to that to something a little bit more than the felt recoil on a standard shoulder-fired service rifle. However, all these recoil reduction measures are necessary due to the sheer power of the cartridge it fires.
The AMR 5075 takes a box magazine inserted on the right side of the weapon at a 45° downward angle. The first prototypes used five-round magazines, but it was also stated that an eight-round magazine was in development at the time.
The AMR 5075 fired a proprietary 14.5mm APFSDS round. The projectile was a solid tungsten, fin-stabilized penetrating dart with a body diameter of 5.56mm and contained in a plastic sabot. Unlike most weapons where they would be designed around an existing cartridge, Steyr designed its cartridge first, then designed the AMR 5075 around it.
It would later evolve into the 15.2×169mm APFSDS round used in the IWS 2000.