Every rifle is an individual when it comes to how well they shoot and what ammo they prefer. Some will shoot about any brand of ammo with acceptable accuracy, others are very picky. You will just have to see what your rifle likes.
Personally, although I handload for all my guns I have had good success with Federal Fusion factory ammo when I use the store bought version. Often times I pick up a box of factory ammo to use for sighting in a rifle, and to generate some brass to start working on a suitable handload.
I would try several brands of ammo or handloads before I would consider messing with the action or barrel bedding. Just make sure your gun is clean and the action / scope mounting screws are all snug before you head to the range.
If you find that the accuracy doesn't meet your needs, now is the time to consider options such as bedding.
The best to you with your new .260
Silvertp