My ProSport is 1 of 2 untouched rifles and I've got and I have 16 of them. I can assure you though the moment it starts to Boing I will be ordering a TbT kit of guides to get rid of that boing. I have done a lot of
de-boinging rifles and only recently my HW80 developed a boing of which I will be sorting out tomorrow with a TbT pro kit. I may be putting the kiss of death on this, but as of yet none of my rifles have lost accuracy by putting a set of guides in them. They are not hard to do, but you get such a sense of satisfaction when your rifle is very quiet and shoots beautifully, knowing you made it that way.