I took a closer look at the stamps. It appears to me that the double "I" may actually be a Roman numeral IV with the V being very narrow. So it might be "Service Model IV", or some such. The much smaller E1 or E7 at the bottom, I have no idea about.
The C.T.G might be assembler or armory inspector initials, but they might mean Cadet or Cavalry Training Gun or Group or some other such thing. It might also be the two periods are just decorative spacers for emphasis, and it means "Cartridge" as opposed to cap and ball. I just don't know.
If S&W tells you anything useful, it would be good to know.
