Gunplummer, I don't know what you mean by "not enough samples tested."
But I agree that some extractors put no pressure against the case. These types don't hold the empty case too well in the bolt face and are sometimes subject to extraction problems.
Which rifle make/models besides the Savage do this? All the Winchester 70's, Remington 7XX and 40X, Paramount, Mauser plus several single shot bolt actions have extractors that press the case sideways against the recessed bolt face and hold it there during extraction.
Doesn't matter anyway as there's not enough slop at the back of the case body to the chamber wall anyway that'll effect accuracy.
Sierra Bullets in the reloading manuals some years ago that loaded rounds rest in the bottom of the chamber due to gravity. Their ballistic tech who tested their bullets for accuracy, a good friend I shot a lot of matches with, knew better and tried to get them to change that. At the time, Sierra didn't. But it got removed some years later.