60-4 3" RB Full underlug questions

[brasspoint]

I have a 60-4 3" RB full underlug revolver and dont understand some of the markings. On the frame by the shroud it has the:
serial number
model 60-4
and then on the cylinder arm is has a very rough engraving that says 1-048 It also has the same rough engraving on the right side of the grip frame. Does any one have these same markings or know what they mean?

Thanks