The AWM in the .338 Lapua Magnum (8.6×70mm) calibre was designed as a dedicated long range sniper rifle. The rifle is fitted with a stainless steel, fluted, barrel, which research has found to be the best compromise between muzzle velocity, weight, and length. The barrel has an unconventional 279 mm (1:11 in) right-hand twist rate, optimized for firing .338-calibre very-low-drag bullets up to 16.85 g (260 gr). When the AWM .338 Lapua Magnum was developed military issue cartridges were loaded with 16.2 g (250 gr) very-low-drag bullets. Longer, heavier very-low-drag bullets like the Sierra HPBT MatchKing .338-calibre 19.44 g (300 gr) and the 21st century 19.44 gram (300 grain) .338-calibre HPBT Scenar can be used, but require a 254 mm (1:10 in) twist rate to stabilize them under high air density conditions as found on arctic coasts.