That would depend on the caliber, and type of bullet, the rifle uses.
The barrel guides and accelerates the bullet out of the rifle, and imparts spin to the bullet to stabilize the bullet in flight.
Yes there are many fine double rifles out there, they do tend to be pricey.
the bullet rises because of the rifling in the grooves of the barrel
The barrel of a rifle is characterized by rifling, helical grooves that impart spin on the bullet, stabilizing the projectile in flight.
The part which the bullet comes out of....
The grooves in the barrel.
One difference is that the inside of a shotgun barrel is smooth and the inside of a rifle barrel is what they call "fluted" which puts rotation on the bullet as it moves though the barrel.
No
Depends on the speed of the bullet, and the length of the barrel. In the case of a .22 rifle, firing a bullet at 1200 feet per second, from a 16 inch barrel, it will take 1/75th of a second for the bullet to leave 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.
Grooves in the barrel. That is called rifling.
how fast it is going