I just got a Savage 99 in 300 savage caliber. Per the serial number look up, it was made in 1937. It has a 22" barrel, ramped and dovetailed front sight, safety on lever and a checkered pistol grip stock. The round counter has an oval window. The lever boss is a "Z" not in a circle. There is a "7" stamped on the bottom of the barrel under the fore end and "SP" in a circle stamped on the left side of barrel by receiver.

I think it is a 99G but not sure. What does the Z, the 7 and the SP indicate? Thanks in advance.