All parts are stamped with the exact same serial number, indicating that they're all original to the rifle.
Well, it depends on what you mean. The caliber is "determined" at time of production based on whatever caliber the manufacturer wants it to be. The caliber can be determined later by looking on the barrel. The caliber will almost always be stamped somewhere on the barrel.
It is the rifling in a mossberg rifle barrel.
Numbers stamped on figurines are usually identification numbers. Most manufactures of ceramics or pottery keep records of these numbers as a mean of identification and production. They may also identify the artisan responsible for the work in some instances.
If you mean a muzzle brake or barrel weight, yes. It can change the vibration pattern in the barrel when the rifle is fired, changing the point of impact. Anything added to a barrel, such as a sound suppressor, will affect the zero.
Most of the numbers are the serial number.
i think that its just storage numbers that they use at stores
Numbers on a coin usually signify the year it was minted.
http://remingtonsociety.com/rsa/questions/barrelcodes
ctg = cartridge
This means established 1820.
They are codes from the canning and the date when the item expires.