Whoa. That isn't why Mini-14 and Mini-30 rifles are inaccurate.
The reason I ask is the Mini-30 scaters Wolf like shotgun paterns because of its .308 bore...I sold it because of that reason. What good is a gun in 7.62x39 if you are foreced to shoot $10 a box commercial ammo.
Mini-14 and Mini-30 variants scatter their shots for other reasons, pencil-thin barrels and gas block interference being a couple. I know, I sold both my Mini-14 and Mini-30 after many trials and tribulations. The only path I didn't take was rebarreling them.
BTW, commercial Winchester 7.62x39 mikes .310'-.311", per my vernier calipers.
Tight-fitting ammo is usually better for accuracy, compared to the alternative. Swaging a .311" jacketed bullet down to .308" during firing isn't the shrapnel grenade people make it out to be, either.
The Ruger Mini-30 has a tapered throat just forward of the chamber, so it can shoot both .311" ammo and .308" ammo. Think of the forcing cone in a revolver, and you get the picture. When done properly, forcing cones contribute greatly to a firearm's accuracy. When added to a gun design that already has accuracy problems, well, it ain't gonna help much. I've got a benchrest-modified SKS that'll shoot into one MOA, but it was a total labor of love to rebuild and assemble, and that's not including my painstaking 7.62x39 handloads. The amount of time and labor that Ruger would have to add to their Mini-30 to shoot one MOA would be way more than the gun is worth.
That tapered bore was Ruger's way of letting their little gun shoot both imported surplus and the .308" domestic fodder available when the gun first came out. Domestic ammo manufacturers have since gone the .311" route with their 7.62x39, see picture above.
As for the CZ-527 and the wonderful accuracy it exhibits, well, duh. CZ has a winner on their hands, they have assembled a quality bolt action centerfire that delivers excellent accuracy, even with crap ammo like imported surplus and Wolf. Do a search online here, THR member Krochus has posted some excellent groups fired from his CZ-527, using both imported surplus, Wolf, and his handloads.
http://www.thehighroad.org/showthread.php?t=184062