Steyr IWS 2000 The Steyr IWS 2000 is an Austrian anti - material rifle created by the Steyr Manlicher to kill helicopters and ligh armoured vehicles . The most interesting of this rifle is his ammunition , that is almost four times bigger than the . 308 Winchester . Description . The development of this interesting weapon began in mid - 1980s , when Austrian company Steyr - Mannlicher AG decided to develop a long - range anti - materiel rifle ( AMR ) - a modern equivalent of the WWII - era antitank rifles . Main targets for AMR are light armoured vehicles , helicopters , installations such as radar cabins , missile launchers , fuel tanks etc . To achieve desired effective range of at least 1000 meters , Steyr engineers first decided to use APDS ( armour piercing , discarding sabot ) , or sub - caliber , ammunition . Development started from 12 . 7mm cartridges , and later Steyr developed a 14 . 5mm APFSDS ( Arnour percing , fin stabilised , discarding sabot ) ammunition in 14 . 5mm caliber and built few prototypes with smooth bores and semi - automatic actions , called Steyr AMR 5075 . Further development led to even bigger caliber of 15 . 2mm fith same ultra - high velocity APFSDS projectiles . This system is called Steyr IWS 2000 ( Infantry Weapon System 2000 ) and currently is probably in Advanced Development status or ready for adoption . IWS 2000 is a very formidable weapon . It fires 20 gramm ( 308 grains ) tungsten dart ( fleschette ) with muzzle velocity of 1450 meters per second ( 4750 fps ) . At 1000 meters this projectile will penetrate a 40 mm of RHA ( rollded homogenous steel armour ) and will result in serious secondary fragmentation effect behind the armour . That said , it will penetrate two walls of any modern APC at one kilometer range . The trajectory is very flat and does not rise higher than 800 mm above the line of sight when fired to 1000 meters . The cartridge is of somewhat original design , and has plastic case with steel head and base . The projectile is concealed within a plastic sabot . The rifle itself also is very interesting . First , it uses rare long - recoil system , when barrel recoils along with the bolt for significant lenght . At the end of the recoil , bolt unlocks from the barrel by rotating and held back , and barrel returns into forward position , ejecting a spent case . Bolt stays at the rearmost position while barrel moves , and then also moves forward , chambering a new round from the side - mounted magazine and finally locking rigidly to the barrel . This design allows for better recoil disttibution over a longer period of time . Huge muzzle brake also contributes to recoil control , so felt recoil of the IWS 2000 is described as a similar to the large - caliber sporting rifle . Five round detachable box magazine is located at the right side of the receiver and inclined down for about 45 degrees . The smooth - bore barrel can be easily detached , so rifle can be carried disassembled into two man - portable packs . Plastics are used where possible to reduce the weight of the gun . IWS 2000 is equipped with bipod and a rear leg under the buttstock . It is also equipped with 10X telescope as a standard . This is probably the most powerful modern anti - materiel rifle , and while it is not a true " sniper " rifle , it is well worth mentioning . The future of this design is also unclear , sice it requires ammunition of a brand new type .