Take to the Mechanic .... LOL
NO!!!!!!!!!!!!!! DO NOT DO THIS!!!!!!!!!!!! Take it to a gunsmith for proper repair.
If you have a Model 30 pump shotgun, the barrel is not intended to be removed by the user. To do so requires specialized tools such as a receiver block and a barrel wrench. You can clean and lube the shotgun with the barrel attached to the receiver. Contact Savage Arms Customer Service and get an owner's manual for your shotgun.
Bore is the number of lead spheres the diameter of the barrel it would take to equal one pound. Ergo, the larger the bore, the smaller the barrel.
1910, give or take a few years.
take out the scew on the bottom side of the barrel
By designer are you asking what Model it is? If so, the Model can be determined by the serial number, which is located on the barrel flats and the forend. You have to take the barrel off the receiver to see them.
100yrs give or take
Should be stamped on the barrel, if not, you should take it to a competant gun smith to have it checked
There should be a screw or release lever under the forearm of the gun. Once you release that you should be able to remove the barrel.
1900, give or take a couple of decades
Serial numbers were not required before 1968. Turn of the century give or take a decade or two.