The correct size of the bullet that fits the rifle.
Depends on the application. If you mean power, the higher the caliber, the more powerful it is. for example, a .22 caliber rifle is much less powerful than a .50 caliber rifle.
It's the caliber of the cartridge it fires.
You will have to me more specific. Do you mean any rifle that fires a 30 caliber projectile or 30/06 or 308?
The standard caliber of a biathlon rifle is .22.
Usually caliber and/or serial numbers.
you will have to define if you mean commercial or wildcat.
a .22 caliber
If you mean the jacket, it all depends on the caliber and maker.
A .177 caliber air rifle has very little recoil.
.223 caliber or 5.56mm.
No You could build a rifle in .306" or any other caliber but you are likely referring to 30.06. A 30.06 rifle is referred to as "30 Caliber" but to be accurate it is nominally .308"
Yes, I can. A Barrett M107 is a .50 caliber sniper rifle.