Sorry, I was on the road when you posted and didn’t have the reference close. Master lock Co. had a history of naming their different lock models until the late 1930’s, your lock was named the Tiger. That name was applied to both versions, 47 steel and 48 brass. Both versions were first produced in 1936 and both were last produced in 1948. It is a lever lock and known as a shell type within Master to differentiate it from the laminated type.
BBE.
