Mossberg
If you know who made it, and they are still in business, probably.
100-400 or so
It is a rifle, 100-300 or so
It's the same as the Mossberg 321
50-100 USD
Try e-gunparts.com
50-100 USD
Mossberg Model 321
Maybe 100 USD
100-450 or so
the Winchester model 100 semi-auto rifle was made between 1961-1975.
100-300 USD