You can try the Gun Digest book of Exploded Firearms Drawings available at http://www.krausebooks.com/category/firearms_knives
It has 975 different firearms although I can't guarantee that the model 1300 is one of them.
Between 110-160 dollars for a model 1300 walnut field grade shotgun.
Email me and I will email you a schematic. Need the exact model number from the left side of the barrel (583.something) sales@countrygunsmith.net
between 200-270 dollars.
http://forum.gon.com/showthread.php?t=155848 http://www.urban-armory.com/diagrams/savage67.htm
Numrich has a gun parts website. Best bet for any gun parts or schematics...
With the XTR marked on your shotgun,this indicates that it was made between 1983-1989.
I see a Model 12, 121, and 1200 but no model 120, so first verify the model number. For a barrel, try gunpartscorp.com, auctionarm.com, and gunbroker.com then start hitting the ads in Shotgun News. The model 120 was really a model 1300 slow budget model. It is the same inside the only difference is the wood on the 120 is plain hardwood. Where as the 1300's were offered with pressed checkering and also in synthetic versions. Here is a link to barrels that are made for the 1300's that will fit the model 120. http://www.midwestgunworks.com/merchant2/merchant.mvc?Screen=CTGY&Category_Code=winchester-model-1300-barrels
Volunteer arms 12 shotgun model 94042?
your model 12 Winchester shotgun was made in 1924.
your model 12 Winchester shotgun was made in 1959.
your model 12 shotgun was made in 1956.
your Winchester model 12 shotgun was made in 1949.