Aluminm: I grind things with aluminum wheels amounts other types, it aint easy even with the wheel spinning 3600 rpm.
I think its another GUL (Gun Urban Legend). The biggest issue might be grit embedding in the rod, easy enough to run your hand down it, if your hand does not feel it you barrel will not notice it. Personally I just don't like the feel of them but I do have several for my pistols.
No matte what rod you use, use a bore guide or you are just looking for trouble. You can scratch the bore. If you clean from the muzzle and don't use a bore guide you will scratch the crown and you will end up having to have it re-cut.
I've been shooting various competitions for over 40 year. Just my opinion but don't discount it.
I don't discount it but I also fail to see the mechanism that causes damage.
The hot gas will eat out the throat in under 1000 rounds on some rifles, many 1500 to 2500. 308 and 06 tend up more in the 5000 round range though likely longer if not bench rest shooting (not that the bench rest shooters shoot them anymore)
I have see the pictures and report of where they shot a gun and established accuracy, then whacked the muzzle about a bit and tested.
They cut it back and increased the damage each time.
I think it was the third or fourth round before they saw any fall off in accuracy.
So, while I am open to discussion, I am also skeptical that anything less than bench rest accuracy is affected by that (let alone scratching.
Having looked at some 25 or 30 rifles not with a bore scope, what you see with a button rifled barrel is an atrocity . Even when lapped they are not great.
Sadly, there is no one who has ever had the resources that could test all that scientifically and come up with concrete results.
As human beings we like our rituals. No issue if it helps but skeptical on the fact part.
I read an article by a guy who interview 15 bench rest buys (top ones). Very few of them used even the same practice let alone the same practice up and down the range of it all from cleaning to reloading.
One guy would swear it was the end of the world if you did not do X, the other guy didn't even do X or swore it was Y that was the end all and be all.
Throw the Virgin in the Volcano, it settles down, ahha, it was the Virgin, last month we threw in a non virgin and it just kept rocking and rolling.
note to self: If you live in a culture that does that, loose the virginity thing at the first opportunity. You may go through quite a few virgins before you realize you are on the wrong track.
The one area I have some belief in is the 22 lands more easily damaged, simply because they are different and not as robust as center fire rifles.