I am definitely not trying to throw shade here, but I would argue that it isn't a "two-shot" rifle, you are a two-shot shooter with that setup. Just like most people. Of course, people don't want to believe that they are the weak link when it comes to shooting groups with light guns using large cartridges. They want to blame the barrel heating up, or other such nonsense, but in all actuality, it is the shooter adjusting their cheek weld, or hold, or follow-through due to recoil that is causing those groups to open up. And no, a lead sled will not take away that issue unless the rifle is set up flawlessly and tightly, and the sled and rifle are set up exactly the same way each shot.
There is a reason why the 7PRC in the Tikka is getting a rep as not being that accurate. One is that the factory loads are not that great, but the main reason is that it is a light rifle shooting a relatively large cartridge. I would bet that if someone tested a 300WM, a 7RM, and a 7PRC straight out of the box all at the same time, there would be similar results across all three, or at least not enough difference between them all to be statistically significant.