Contact the maker.
Yes,www.proofhouse.com
Contact the manufacture or look it up in a Bluebook of gun values.
A gun manufactured by Browning Arms
Contact the maker if still in business. If not, try the Blue Book of Gun Values.
From what I could find your gun is made by Winchester. It should say it on your gun somewhere though.
Such an item would be a custom piece. None are manufactured in that configuration.
You ask the question here. State the model number and who manufactured the BB gun. I need those 2 items in order to give you an answer.
A cannon
Blue Book of Gun Values or proofhouse.com.
This gun was manufactured between 1954-67. If you want to get it repaired go to the Crosman home page and click on "Find a service center" It will guide you to a repair location. See the related link.
USA if you mean Ruger.