The direction of the spin which is put on the bullet by the rifling.
Ballistic spin drift is the tendency of a spinning projectile (such as a bullet) to drift slightly to the side due to the gyroscopic effect created by its spin. This effect influences the trajectory of the projectile and can cause it to deviate from its intended path at longer ranges. Shooters need to account for ballistic spin drift when calculating their shots for increased accuracy.
The answer has two parts - 1. Why do you want it to spin: It allows the bullet to be more accurate and travel further. The bullet spins for the same reason that football players spin a football when they throw it. 2. Why does it spin (How do you make it spin): Inside the barrel are grooves (rifling) that catch part of the lead of the bullet and spin it like bolt spins when you put it into a nut.
The rifling in the barrel. These are grooves cut on the interior of the barrel that twist around and cause the bullet to spin as it passes down the barrel. The spin stabilizes the bullet and promotes accuracy.
Because a spinning bullet travels in a straighter line, for further, than a bullet which is not spinning. So, in a word, "accuracy" is why a gun puts a spin on a bullet. Not all of the guns put spin on the bullet though. Those that do have rifled barrels(grooved on inside). There are also smooth bore guns that do not cause the projectile to spin.
Rifling causes the bullet to spin through the barrel and downrange. This spin stabilizes the bullet, allowing it to maintain a straight course to the target. Without the spin, accuracy would be dismal.
A bullet rotates in flight due to the rifling inside the barrel of a gun. The rifling creates grooves that grip the bullet and cause it to spin as it travels down the barrel. This spin stabilizes the bullet's trajectory and improves accuracy.
The barrel guides and accelerates the bullet out of the rifle, and imparts spin to the bullet to stabilize the bullet in flight.
It can. The rifling in the barrel causes the bullet to spin. This usually keeps the bullet moving relatively straight (because of gyroscopic stabilisation). However, as the bullet slows down at longer ranges, the spinning can cause it to wobble and drift. This is called spin drift. Spin drift can be upwards, so yes, rifling can cause a bullet to go up, but only at extreme ranges.
The purpose is to make the bullet spin as it leaves the rifle. The spin makes the bullet travel in a straight line, and allows for accurate shooting at longer distances.
The grooves in the barrel.
The direction of the Earth's spin and the direction of the Moon's orbit is the same - counterclockwise