The 03A3's were made by Remington or Smith Corona. Odds are the rifle has gone through some kind of rebuild (which is ok) and no longer has all original parts. The good news is it's easier to locate and identify Remington parts than it is to find and ID Smith Corona parts. Most of the Remington parts will be stamped with an "R" somewhere on it. I have two of both and I am still looking for an original stock for one of my Smith Corona's to complete the setbut they are very hard to locate. Unless you know what to look for it's very hard to tell the difference between a Remington stock and a Smith Corona one, but you can tell.

They are a great peice of history as are the original Springfield 03's,(I have a few of those too)try tokeep it in it's original condition if you can. I'm not against sporterizing per say as I have done so onthree 03A3's but all were modified in such a way when I got them that putting them back to original condition was not an option so I made very nice sporting rifles out of them. They are extremely strong actions, one of mine is a 300 Winchester mag and it shoots fantastic.

Congrats on the rifle, hang on to it for the next generations to admire.