Grooves in the barrel. That is called rifling.
The barrel inside has carvings in it so the bullet is more accurate and goes a longer distance. I believe that is the case.
The grooves in the barrel.
Rifling. The barrel is not smooth on the inside. There are small grooves spiraling down the barrel which makes the bullet spin. Nearly all shotguns do not have rifling in the barrel.
Rifling. The barrel is not smooth on the inside. There are small grooves spiraling down the barrel which makes the bullet spin. Nearly all shotguns do not have rifling in the barrel.
The grooves (rifling) cut into the barrel.
The bore is rifled so as to put a spin on the bullet. This spinning gives a greater accuracy to the bullet, especially over that of a smooth bore.
A rifle can fire a bullet accurately to a longer range than a handgun. However, some handguns can fire a bullet just as accurately, and sometimes moreso, at certain ranges.
You will have to state whether it is a rifle or handgun to get an answer.
If you're referring to a cartridge for a handgun or rifle, there are only 4 parts. The case, the primer, the powder charge and the bullet. "Bullet" actually refers only to the piece of lead.
Probably, almost certainly, the .600 Nitro Express is the overall most power handgun bullet. Let me alter this answer by saying the .600 Nitro Express is a rifle round that one company made a pistol for. The most powerful handgun cartridge is the 500 S&W Magnum.
There is no difference, they both do the same thing. Using the analogy of a gun (firearm) for example: a handgun, which is easily concealed upon a person, shoots a bullet; a grenade is equally concealable. An aerial bomb and a rifle (which shoots a bullet) are not easily concealable upon a person. The handgun is to grenade, as the rifle is to (an aerial) bomb.
Handgun projectiles are fired through shorter barrels which lead to a reduced production of muzzle energy.