There are no studies or peer reviewed journals on damage caused by not using bore guides.
We *all* know you're never supposed to clean from the muzzle end of the barrel, because you can possibly cause uneven friction wear at the crown from running the cleaning rod against it repeatedly. Logic says the same exact type of damage can happen at the chamber end- to the lands in the throat. Unless the rod is supported so it remains centered as it enters the chamber.
With all the custom barrel makers and fancy gunsmiths out there with bore scopes, you'd think there would be some photos on the web. Or at least ONE photo.
