That might be for the AR type rifles, but what about all the OTHER rifles without charging handles? Seriously, if you can't maintain a consistant position without the aid of a charging handle, you have a problem. I think those groups went awry because those shooters were NOT USED to a different position. I put my head down the same place on most all my rifles because of muscle memory - I know where my head is supposed to go cause it feels the same every time. It also helps because when I shoot my FAL's, bolt guns, shotguns, whatever - my head is in a consistant place regardless of what I am shooting and makes me more consistant overall. If the only rifle I was ever going to shoot was an AR, then an index would be of use. Most people I know who nose-to-CH don't touch the CH with their nose, they are backed off, which is then no different that placing ones head anywhere else on the stock (if your nose isn't touching, how do you know how far back to put your head?). I suppose some actually maintain contact, but none that I know personally. Most I know touch, then back off to a personal point, which is what I do it's just I back waaaay off. As Kisara said, consistancy is the key, and I simply don't reply on a charging handle to make me that way, I train my body just as I train when using handguns, shotguns, or bolt guns. Whatever works for the individual though....