Isn't accuracy depended on a lot more functions than the action? I highly doubt that a regular bolt action rifle from 50 years ago could compete with the semi-auto PSG-1 or the M-25 in accuracy. Plus there are custom manufacturers of semi-auto precision rifles that are on par with any bolt action rifle out there. An example of such is Blake's Custom Rifles outside of Las Vegas and the more famous Les Baer. Of course, a poorly made semi-auto weapon can damage ammo while cycling not enough to be disasterous but enough to effect accuracy. But the majority of accuracy issues are solved by having higher standards for production.