Havlin's book on Mossberg history should have the answer.
You will have to call Mossberg
You will have to contact Mossberg to find out.
Mossberg made all their rifles in the USA.
There isn't any. Mossberg did not put serial numbers on their rifles until 1968
Mossberg manufactured several models of .22 rifles, with the most notable being the Mossberg 44 series, which includes the 44US and 44B models. The Mossberg 702 Plinkster is another popular model known for its lightweight design and reliability. Additionally, the Mossberg Model 351 was a semi-automatic rifle that gained popularity in the mid-20th century. These rifles are well-regarded for their accuracy and versatility, making them favorites among both beginners and experienced shooters.
The Lakefield factory in Ontario Canada has made rifles for a number of different brands, Cooey, Lakefield Mossberg, and now they manufacture all of Savage's rimfire rifles. Its no surprise if they use the same detachable magazine.
Winchester, Mossberg, Remington
2002
There were several Mossberg .22 rifles that load through the stock. The 51M, 151K, ect. These have a removable inner rod that is draw back through the buttplate, and cartridges are inserted into an angled hole in the side of the stock. Mossberg also made rifles that loaded from a box type magazine, and an under barrel tube magazine. There are more than 100 different Mossberg 22 rifles made.
My catalogue states that the rifle was made by Mossberg (Model 320-321) Mossberg made a variety of single shot and repeating bolt action rifles starting in the 1930. they were low-priced and were intended for extensive use. However it does not state when they stopped making these rifles. About 30 different models were made.
Mossberg made Westernfield shotguns and rifles for department stores. My Westernfield shotgun is identical to a Mossberg 500.
ABOUT $125-$150, depending on condition. Nice rifles.