Does the serial on the bolt match the rifle ? I think one of the other posts was asking about a flat bottom stock, he may have been asking about if it was the BR stock, that is how I took the question.
With the hand stop, it makes it more clear that it is a 40X and not the 40XBR stock, which would be the correct stock. Still, the carbon barrel makes it a earlier model as long as it is the factory installed barrel. The things with the 40X's, people swapped parts on a regular basis to make a complete rifle. Your rifle sounds correct for a earlier model.
I have seen a 40X action, with a newer 700 bolt swapped in and it was sold as a early 40X on here and the seller was asking 40X prices. True it was marked 40X, but when in reality it was just a nice varmint rig and not a collector type rifle. Pics would help on your rifle if you wanted to post them. Sounds like you may have a nice, older 40X.
A very nice, older 40X just sold on this forum a few days back and it was all correct. I had my hands on that rifle and it was a very accurate and very nice example of Remington's finest work back in the day. Someone out there purchased a nice rifle for a collection and a great shooters as well.
Someone else had a 40X stainless action for sale at a crazy price. It was a 40X action in stainless, but for a rifle to build on, other than the 40X designation, which a a lot of people want (nostalgia) me being one of them, a Remington 700 RR single shot stainless action is just as straight for a lot less money, if you can find them even. The 40X means a lot to some and I do like them.