Rifled muskets were smoothbore firearms returned to the armory or contractors for rifling. These striations are due to the rifling inside the barrel of handguns. Another feature of this pistol is the use of polygonal rifling in the barrel bore. S&W barrels also feature polygonal rifling. A smoothbore weapon is one that has a barrel without rifling. The Desert Eagle's barrel features polygonal rifling. The rifling in the barrel has a unique 13&colon;8 twist. ACP barrels deviate from the other models having polygonal rifling instead. The barrel has a six-groove rifling. It has a longer and heavier barrel with revised rifling, and a bipod. The barrels could have traditional rifling or polygonal rifling. The grooves most commonly used in modern rifling have fairly sharp edges. Nor did it require rifling or recoil mechanisms. Supporters of polygonal rifling also claim higher velocities and greater accuracy. It was long overall, had a bore length of and a rifling length of .