Rifling is a process of putting spiral grooves in the barrel of a gun. These grooves give the bullet a spin as it leaves the barrel. The spin makes the bullet more stable in flight, giving it a straighter, more accurate path. There are two types of markings that rifling produces: land and groove. Land marks are the high points between the spiral grooves. They are raised up above the level of the grooves and are smooth. The groove marks are the low points between the spiral grooves. They are sunken below the level of the lands and are also smooth.