Witness marks.
This will not fit a model 12
Your winchester model 12 shotgun was made by winchester in 1928.
Your winchester model 12 shotgun was made by winchester in 1950.
Your winchester model 12 shotgun was made by winchester in 1956.
Your winchester model 12 shotgun was made by winchester in 1939.
Your model 12 Winchester shotgun was made by Winchester in 1926.
your Winchester model 12 was made in 1970.
Your winchester model 12 shotgun was made by winchester in 1937.
Your winchester model 12 shotgun was made by winchester in 1947.
Your Winchester model 12 shotgun was produced by Winchester in 1936.
your Winchester model 12 was made in 1913.
your model 12 Winchester shotgun was made in 1914.