Benjamin made a 137 pistol not a 137 rifle. They did make a 317 rifle, is this what you are asking about?
The pistol model 137 was made between 1946-85 the rifle model 317 was made between 1940-1969
It was made between 1969-1992. That is as close as I can date it. You may want to write to Crosman airguns ( they own Benjamin) and try to get more information.
It was made in 1981.
Today Crosman air gun co owns the Benjamin line of airguns
Your model was made in 1969.
See the link below.
1983
It was made in 1970
1978
It was made sometime between 1969-92.
serial number T170160 would have been made in 1973.
This pistol has not been made since 1941. Your best bet is the web, someone like gun brokers or guns America.
This is the best I can do. (see the link below)
you need to state the model number not the serial number to get and estimate of value.
T427432 was made in 1982.
1980 see the link below. See the link for your date of manufacture
It was manufactured in 1979
it was made in 1975
It was made from 1946 to 1985.
The model 132 was made from 1942 to 1986.
If it's T123136 it was made in 1972
It was made sometime between 1969-92.
Around $50
I think you answered your own question. It's a combination BB and pellet rifle. I can add this information. It was made between 1969-86. It a pump rifle using the forearm as a pump. The name Benjamin Franklin was a marketing gimmick. Ben Franklin had nothing to do with it. Walter Benjamin started the company in 1899 and today it's owned by Crosman Corp.
I suggest you go to Crosman.com and click on Support and ask your question there. Crosman owns the Benjamin line of air rifles
serial number T170160 would have been made in 1973.