 Micro-vibrations acting during the bullet's passage result in differences in trajectory as the bullet exits the bore, which changes the point of impact downrange.A free-floating barrel is one in which the barrel and stock are designed to not touch at any point along the barrel's length.The barrel is attached to its receiver, which is attached to the stock, but the barrel "floats freely" without contacting any other gun parts (except the front sight, which is often mounted on the barrel).