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