If it doesn't say Lefever somewhere on the gun, I don't think you have a Lefever.
In order to determine the age of Lefever shotgun, the serial number must be known. However, Lefever shotguns were only made and distributed between 1885-1916.
LeFever is one.
Your shotgun was manufactured in 1923, by Ithica Guns which took over the Lefever brand when they acquired the corporation in 1916.
The average cost of a Lefever Nitro Special shotgun at auction is $650. This amount may be higher or lower depending on the condition of the gun.
Ithaca Firearms manufactured the Lefever Nitro Special shotgun with serial numbers between 101600 and 119899 in 1922.
The Lefever was mfg. in 1935.
If it is a double, remove barrel and you will see it along with serial #.
Examine with high power magnification.