Numrich's cross reference list shows the 488A to be the Mossberg Model 51, produced only in 1939. The 51 was apparently a varient of the model 50, produced from 1939 to 1942. Production shut down more than likely to WWII, not because it would be easy to convert. I don't know of any huge collectability of Mossbergs, but there might be something out there.