There are undoubtedly some lots of factory ammo in many calibers that would shoot very well, but in all probability, you can work up a handload for a particular rifle that will outperform almost any
factory stuff. And, this is also true of load performance charactaristics other than accuracy (velocity, bullet type, etc.). There are many different calibers for which high-performance factory ammo is just not avaliable. Calibers for which I have found it possible to greatly exceed the performance level of any factory ammo available in the U.S. include 7X57mm Mauser, 7mm Remington Magnum, and 8X57JS Mauser. And there are others as well.

Keep yore powder dry!!