Nice looking sporter.

Is the wood cut out/inletting for the bolt handle and the sight newer/more recent than the action inletting?,,no oil staining? or is that just the light and pics. The bbl inletting looks like that also.

If it is, might the bolt have been altered from it's orig Military form to the present shape when the scope was added at a later time?
The adj rear might have been an addition at that time too or maybe just the long slide edition. Or perhaps it got a new bbl minus an orig rear bbl sight and didn't have the rear aperture sight at all when made..
All speculation of course because I'm seeing the wood inletting of those parts appearing done later in the life of the rifle.

The straight shank handle bolt was the standard on the single heat treat '03. The slight sweep to the rear started somewhere in the early double H/Treat.
But I don't know if RockIsland '03s' follow the same track in that styling.

The trap door butt plate first reminded me of the Mannlicher Schoenaur sporter BP. But the serrations looked a bit too bold. Not that I've seen all ever made of course..
Maybe it's a Mauser sporter trap butt plate. They had two styles available. One hinged from the top, the other at the bottom. I seem to recall they were serrated heavier than the M/S's which I have.
I don't have the K-action sporter anymore to refer to and the Speed's Book on Mausers is stashed away somewhere. I know there's pics in there.