I might as well weigh in on this one..
Frank, your friend's barrel had something really bad happen to it and I just do not know what to tell you except send it to the manufacturer for evaluation or replace the barrel. I have yet to see this kind of damage in a barrel be close to accurate.
most of the spuds I have used were aluminum or nylon coated steel, I do not see this kind of damage coming from even exposed steel spuds for bore sighting. these are sharp and very deep. spuds would be rounded and smashing kinds of damage
a SS brush and drill, I would say, not likely. I would expect to see much more less defined damage than just a few annular rings but never as deep as this damage is.
this damage is screaming hardened steel bur or cutting edge on a tool. the tool only made a little more than one full revolution each time. the more I look at these picks the more I am convinced this is an act of stupidity, ignorance or malicious intent. I am going to weigh heavily on Ignorance or stupidity on this one. these grooves were cut, not abraded, not crushed into the bore, these grooves had to be cut with something meant for cut metal. These grooves remind me of threading tool marks. single point threading tools I used to work with at A.C. Machining.
the more I look and and scrutinize the grooves, this had to be something going around, wobbling, aluminum cleaning rod, grit or hardened steel sliver stuck in an aluminum rod, this is more and more looking like a perfect storm of ignorance
The only other way I can see these grooves could have been made is a drill, a patch covered brush and some silicon carbide abrasive from a blast
