underside of bolt markings are typically lot codes for the steel used. It just so happens the one flaw in my Remington 1903a3 is it has a smith corona wide grid type butt plate - parkerized in near perfect condition. I'll take a pic if you might be willing to trade.
I don't have a smith corona...yet. I've been waiting for the right sporter to speak to me for bringing back to serviceable configuration and condition. I do, however, have a very nice smith corona typewriter that I restored dating to just before they started making rifles. I use it to type out my restoration notebooks.
You can look up lot codes here. http://www.vishooter.net/m1903.html
Thanks for the lot code info. My butt plate is in pretty rough shape, had some rust like the gun was sitting on the ground or something. Would I be correct in assuming that the butt plate should be blued on an SC as manufactured?