I have a J C Higgins rifle which is a clone of the Model 80. I narrowed down the date of manufacture in two ways. I saw that it had Micro-Groove rifling, so it is after 1953, and it has a 24-in. barrel, which I believe was shortened to 22 inches in 1958, so I figure mine is between 1954-57. I am more confident in the Micro-Groove dating than the barrel length dating. I based the barrel length data on old Marlin ads for sale on E-bay. I am sure others have more information on this. As to the magazines, I bought a couple from Dick Williams and paid $45 for them, shipping included.