Springfield 1903 NRA Sporter???

[Harlan (Deceased)]

As said above, it's an early 1903 'Mark I' variant that's been through at least one arsenal rebuild (most parts refinished and swapped around by the military) and the barrel was most likely changed to a 'then' more modern WWII era HS replacement barrel.

Many new HS barrels were scrapped after the war and bent to take them out of service, but later straightened and sold as good barrels.
(Just something to keep in mind)

It still would have had some collector value after being rebuilt by the military, and 'some' people would have possibly given it a little more value, though being rebuilt, just for the fact it was a 'Mark I' variant at one time. (Some would not)

Sadly, as far as collector value, it was later 'sporterized' in the private sector after released from military service to look more like a modern hunting rifle sometime in the past, and it now has very little resale value left, other than for the few parts that haven't been altered.
The original stock is gone and the original Mark I receiver has been drilled and tapped for a scope so it has almost no resale value now.

Many, many old milsurp rifles were done this way, especially during the 50's and 60's because they were an inexpensive substitute for a much more expensive hunting rifle back then. Modern hunting rifles during that time period were expensive and nobody thought anything of sporterizing old milsurp rifles to be hunting rifles because people could buy them out of barrels at that time for around $20.

Your late father-in-law was probably proud of it at one time in his life and he may have possibly done the work on it himself in his life.
I'd keep it as a family heirloom and have fun shooting it. With the HS replacement barrel, it might make a great and accurate shooter, depending if the barrel was indeed replaced by the military during an arsenal rebuild.

It's not a piece of junk if the barrel is good, and it might make a great hunting rifle with family history attached.
If it were mine, I'd have it checked by a gunsmith and then take it to the range to see how it shoots. It would be nice if it groups well (probably will) and you can keep it alive!

It just has very little resale value left. In my area an arsenal rebuilt, sporterized, D&T'd Mark I in an aftermarket stock would sell slowly for around $200 - $250.