A concept from WWI, the heavy anti-material rifle, which used to be called the anti-tank rifle , but following WWI, tank armor became thick enough where the only areas on most tanks that could be reliably damaged with a rifle were the tracks and the vision blocks or periscopes. With the change in tank design, the heavy ( and I mean heavy, like around 40 pounds) rifles evolved to slightly different purpose.
Anti material rifles are intended for long range destruction of light armored vehicles, soft skinned vehicles, missile launchers, aircraft (on the ground) and other high value targets. They are not intended for use against enemy personnel, however the lighter AMRs like the .50BMG have often been used as sniper rifles, especially in a counter-sniper role.
The Steyr AMR/IWS 2000 (Infantry Weapon System) is chambered in a 15.2mm cartridge, which is fired from a smooth bore barrel, like a modern tank round. The rifle operates on a long recoil concept, in where the barrel recoils along with the bolt, allowing for the felt recoil to be reduced by spreading it out over a longer period of time. The barrel is also able to be quickly detached to allow the weapon to be broken down and carried by a two man team. The ammunition is an armor piercing, fin stabilized, discarding sabot, of tungsten alloy or depleted uranium. Notice the massive, multi baffled muzzle brake on the IWS version for reducing the recoil of the massive round. The recoil has been reported to be similar to a big game rifle. Tungsten and Depleted uranium are used because they have a density much greater than steel and can therefore be driven into armor in much the same way as a galvanized steel nail is driven into a soft pine board.
Right after the projectile leaves the barrel, the walls of the sabot break away as seen above, releasing the rod-shaped, sub-caliber penetrator. The fins at the rear of the penetrator spin to give it stabilization in flight. The small diameter of the projectile versus the cartridge and powder charge gives it truly astonishing velocity,somewhere around 4750 feet per second, combining with the super dense construction of the "bullet" to make the capable of penetrating 40mm of rolled homogeneous steel armor at a range of 1000m. Very few weapons can achieve that type of penetration and almost none at that range. Another advantage of a weapon system like this is that it would likely cost less than a Javelin missle system or other ATGMs that might be used to fill its role. A top quality AMR like the Steyr would be very useful for smaller armed forces that do not have the massive air wings and precision munitions that would be used for many anti- materiel missions in the US Armed Forces.
STEYR AMR/IWS 2000 Austria
Operation: long recoil,semi-automatic