The US Governent's defense laboratory Sandia has developed a bullet which incorporates a self-guidance system, allowing it to hit a target up to a mile away with impressive accuracy. The four-inch long slug incorporates a lot of technology: an optical sensor in the nose used to detect a laser-guided sight, an 8-bit central processing core, and a set of tiny actuators which steer the bullet using fins mounted towards the rear of the casing. However, unlike guided missiles, the bullet doesn't require an inertial measuring unit owing to the dramatic difference in size.
Whereas regular bullets need to spin to maintain a straight trajectory, Sandia's new bullet's fins allow it to fly perfectly flat like a dart. This aerodynamic stability not only aids accuracy, but also helps improve the range of the shot. The bullet's able to correct its trajectory over 30 times a second, with the unit travelling at speeds up to 1600mph (Mach 2.1) using conventional gunpowder as a propellant. Interestingly, because of its active correction and it settling in the air over time, the bullet actually becomes more accurate the farther it travels. It's not yet in production, but the team say they envision it being used by the military, law enforcement, and even hobbyist shooters.