Saw your earlier post and have not been able to find any info as to manufacture date. I have a model 59 that belonged to my late stepfather.
Unfortunately,I have no way to date it. I do know he had it in 1957 when he and my mom married. It looked old to a twelve year old at that time. I also know he and I took many rabbits and squirrels with it over the years.
J. Stevens Arms Co was taken over by Savage Arms Co. in 1920. However they continued to manufacture firearms under the Stevens name.
Sorry I can't be of more help. I continue to search for more history on these older guns.
I don't believe these could be rifled to accept the .45LC cartridge. Doesn't appear to enough meat in the barrel to survive rifling. Just my thought.