The Anti-Materiél Rifle 5075 (AMR 5075 for short) is a prototype Austrian anti-materiel rifle developed by Steyr Mannlicher.
When the IWS 2000 was developed, the AMR 5075 was conceptualized as a design proposal for a semi-automatic variant.
The AMR 5075 is a semi-automatic anti-materiel weapon that uses a long recoil system, i.e. the barrel and bolt recoil together when fired. It is, in fact, the same recoil system as used in the bolt-action IWS 2000. The barrel and bolt recoil backwards almost 10 inches (25 centimetres) when the weapon is 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.
Like with the IWS 2000, the AMR 5075's barrel is not rifled, but is actually smoothbore to help accelerate projectiles and improve ballistic effectiveness.
The AMR 5075 takes a box magazine inserted on the right hand side of the weapon, with the magazine well having 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 fires a proprietary 15.2×169mm APFSDS round. It contains a fin-stabilized, dart-shaped penetrator of either tungsten carbide or depleted uranium, capable of piercing 40mm of Rolled Homogeneous Armor (RHA) at a range of 1000 meters, and causing secondary fragmentation. The cartridge is comprised of a plastic case, a steel head, and a plastic sabot shell around the penetrator.
Test results had shown that the penetrator has a much flatter trajectory than the .50 BMG round.