What an awesome shotgun!! You have a real gem. I'm not sure what year your gun is, the only thing I know about LeFever Arms Co. is that they were in business from 1880 until 1916 when they got bought out by Ithaca Gun Co.
Daniel Myron LeFever is credited for the mechanism to automatically eject the shells when the breech was opened and making some of the finest double barrel shotguns in America.
Is it in working order? If it is, how do you like it and how long have you owned it?