"Back to the "R" thing. I said before, I just guessed at the model, not really knowing how to identify.. Is it really an "R"? If not, what model would it be with a 1948 serial number and the rounded forend? How to tell?"
One possibility is that the forearm on your rifle is not original to that rifle. The forearm, buttstock, buttplate, and frame should have matching assembly codes. Unfortunately, you have to pull the buttstock to find the assembly code on the frame. (On Utica guns serial numbers were used instead of assembly codes, so the forearm, buttstock, and buttplate numbers matched the serial number on the bottom of the receiver.)
