Which Model are you asking about.
The model 100 was made between 1935-1941.
It's usually on the breech or the very back of the pistol.
It was made from 1946 to 1985.
It started in 1946 to 1985
Benjamin made this model from 1946 to 1985, but did not start serializing them until 1957. I also have a Benjamin Franklin that has no serial number. Before 1957 it is not possible to set an exact date. Just know it's OLD. The 137 is a .177 caliber pellet pistol the 132 is a .22 caliber pistol and the 130 is a BB pistol.
Auction
It would be worth between $60 and $80.
It was made between 1935 - 38 see the link below for the owners manual. it's a model 107 or model 177
for people to be great inventors
It depends on the Model, Age and Condition of the pistol. Benjamin pistols are still being made today. Benjamin is currently owned by Crosman air gun company.
It was made in 1976. It's part of a series of 3 pistols (130 Series). It's either a 130 - BB, a 132 - .22 cal or a 137 - .177 cal pistol.