fuzebox, you have the A1 closed bolt, not sure what version, but they all took the same mag. The mag is the same one the Model 80 bolt action uses.
http://www.gunclips.net/mamo7822boac.html
What Lanzerac was saying about the "semi-smokeless" and "smokeless", was critical in the open bolt Mod 50, not so much in the closed bolt. The open bolt had a part you could change inside the receiver to cycle either round. It was the early version of "Standard velocity" and "High velocity" today.