Stevens was in business from 1864-1950. They did not have a "pocket pistol" model, but DID make a "pocket rifle" model from 1869-1916. Am aware of no specific production data based on serial numbers.
The stevens Model 35 offhand shotgun(even though it is listed as a pistol) was made during the years 1923-1935 in .410 gauge.I do not have a model production breakdown by years with serial numbers though.Maybe savage/stevens might have more info at the savage arms web site?It would be worth a try.
Check the receiver and barrel
Buy one of the books that has published serial numbers for that particular pistol.
You can look up serial numbers at Proofhouse.com
Go to the library and look for Flayderman's Antique American Firearms. You should be able to identify your pistol from the pictures and descriptions in the Stevens chapter.
The only way to find out how old a Bretta automatic pistol with the serial number 605222 is to call the company. There is not a listing for Bretta's by serial numbers online.
serial numbers are of no value without the makers name, model of pistol, caliber and overall condition.....................
AFAIK, there is no published data on Llama serial numbers.
Impossible to answer.