Hesalite: I don't know what the odds of finding a "3" bolt head on a virtually unused No. 4 would be but I wouldn't think it would be high. On the other hand, a former owner/ tinkerer might have put a "3" on it to tighten up headspace to the lower limits and for no real reason. I have a Longbranch with a really big "3" on it that was set up by a target shooter to just barely allow the bolt to close on thicker rimmed brass. Gauging it showed I could easily get acceptable headspace with a normal "1" or "2" bolt head. Getting back to your rifle, the only thing I see in the photos that I wonder about is the strap at the rear of the forend. To me that doesn't look like the way they came from the factory. Is the forend Savage stamped?

Ridolpho