This will not fit a model 12
A Winchester model 1906 in the condition that you describe will bring between 275-400 dollars on today,s market.
Remove the stock and you will see what is keeping the bolt from sliding out.
Numrich gun parts corp.(E-gun parts.com).
Model 70 Winchester delux 348 i think.
Leave this to a gunsmith
700 ADL Long Action
Lever action, blued steel, wood stock, most likely chambered in 30/30