Did Remington duplicate 1903A3 and 1903A4 serial numbers, requiring them to add a Z with a handheld stamp after the initial serial numbers were roll stamped?
It's been heavily sandblasted, and some of the serial looks redone by someone. I think someone tried to enhance a weak serial number. The finish looks like a civilan repark.
If the roll stamp looks good on the other side, I think it's just one someone refinished and tried to restore the serial that was washed out.
Here is an original roll stamp with the original park to compare.