Tom,
Jim Carmichel wrote many years ago, before I'd ever published a gun article, about shooters attempting to "accurize" rifles they'd never shot in the first place. His favorite example was a walnut-stocked Ruger 77 in .220 Swift that shot so well, right out of the box, that he used it in some local benchrest matches, astonishing the guys shooting custom rifles in more "suitable" cartridges.
One of my favorite stories about factory rifle accuracy (which might also apply to at least one other current thread on this forum) I already told in OBSESSIONS OF A RIFLE LOONY, but bears repeating. Many years ago, when Dave Talley was still living in Glenrock, Wyoming, I was down there hunting something, and Dave told me the story about a Really Famous Accuracy Gunsmith who'd come out that spring to shoot prairie dogs with him.
The RFCG brought one of his own rifles chambered in .223 Remington, along with a short ton of handloads worked up for the rifle. When they went to the range to check the .223's zero after the plane flight, the really special trigger broke. Of course, even if a new trigger could be shipped overnight in they'd lose a couple days of shooting, so they went to the local shooting store and the only .223's in stock were Savages. So the RFCG bought one, I believe for around $200, and in Dave's shop mounted the Swarovski scope from his super-accurate .223.
They found the really special handloads fit just fine in the Savage, and at the range found the Savage shot just as well as the super-custom rifle. Whereupon the RFCG turned to Dave and said: "Don't you DARE tell anybody." Of course, when I showed up that fall Dave told me, but I have kept the name of RFCG a secret.
