Bob,
Have heard that info about the change in #9 before, perhaps from you.
All I know is it used to get copper out years ago, when left in long enough. Or at least it appeared to, before I had a bore-scope.
Then, t number of years ago, #9 quit working, at least in a normal human lifespan. Tried #9 Benchrest and it worked a little better, maybe as well as the original #9.
After buying a bore-scope maybe 10-12 years ago started letting it decide how much copper was removed, and how fast. Found out some products that were considered hot stuff didn't remove much copper, or at best worked very slowly.
But also started experimenting with not cleaning bores, and seeing how long accuracy held up. Of course, it depends on how accuracy is defined, but found a lot of barrels could go a long time, often several hundred rounds, before accuracy dropped off.
As a result, I don't clean barrels unless they need it anymore, but when I do, prefer something that will do it either in less than an hour or overnight, depending on my schedule. As a result, haven't used any of the Hoppe's products in quite a while.
