Yep, always good to leave things alone whenever possible. In an earlier post, I mentioned that at one point I used some very fine sandpaper (1500 grit, I think) on the ramp because there were machining marks that I could see but not feel. I did not succeed in removing (or even diminishing) the marks, and I was afraid to get any more aggressive with it. In any case, it did not improve the FTF problem, and I moved on to playing with the OAL of the ammo.
I sense that there is an untold story behind your admonition. Care to share? I'm always interested in learning what NOT to do, and why.
Thanks,
John