Anyone out there have any experience with the Limbsaver sharpshooter X-ring?? I have a friend who is considering trying it on a rifle and looking for some honest input. He has tried lots of factory ammo and just cannot find one that will shoot better than 1.5moa @100yds and wants to try this product to tighten his groups. He don't reload so he is looking for a way to improve the accuracy on his rifle. It is a hunting rifle, but like everyone else he is trying to squeeze every ounce of accuracy out of it he can. Is it a gimmick or for real??