The Lefever was mfg. in 1935.
If it is a double, remove barrel and you will see it along with serial #.
estimated value of a double-barrel J T randall shotgun
Requires professional appraisal.
Turn of the century.
The best that I can do is say that the Lefever Nitro special was made from 1921-1948.
Blue Book of Gun Values
To get a parts breakdown you would need to take the shotgun into a gun store. The store will be able to provide an estimate, or order new parts.
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when did the make the smithsonian double barrel shotgun