I actually have this on my KP-06, and yes it does scratch the inner barrel (Falcon 162.5mm 6.03mm tightbore, nothing significant and i do not suggest you affix this to an aluminum barrel i.e. madbull tightbores) however i too fret that if i screw in any type of flash hider or silencer on the threads it will bend/disfigure the barrel, so i just keep it on to hide the inner barrel sticking out