Impossible to answer without a detailed description of all markings, caliber, bbl length, grip material, type of action.
Without a serial number, there is no way to answer.
If you go to Smith and Wesson,s sight they should have a service booklet that was issued with this handgun showing proper dis assembly and cleaning procedures.
Standard Catalog of Smith and Wesson
1855
You will need to buy or find a copy of the Standard Catalog of Smith and Wesson.
@ 1943
1995
27 years old
@32 yrs old
1972
1983-1988
Standard Catlaog of Smith and Wesson has sn data. Call S&W and they will tell you when it left the factory.