I traded a M&P 9C for mine to a retired Chicago cop. He just wanted a larger gun and I wanted a smaller one. He told me that the gun had gone back to Kahr for a feed ramp issue, and they had polished the entire guns internals and the barrel on the house. I completely believe him, as he was the least handy person I ever met, he even took 2 perfectly new kahr mags and sanded down the bases to get rid of the extended finger rest, ruined both of them by sanding or grinding all the way through to the pin.
I know if he had touched the gun, it would be obvious. So 2 pierce mag finger rests and I had 5 plus 1, 7 rounder I purchased, gave me 6 new mags.The gun is smooth as a newborns rear. They even polished the mag release and trigger, it looks like nickel. Very nice little gem.