When I lap it, I sand just enough to remove most of pattern and the burr. If there are any low or high points, they show up immediately.
I agree. I have been urging everyone who does a barrel change to do just that. A sound practice in my opinion.

I never thought of burnishing as a step that produces a pattern in the metal, but rather smooths out any irregularities.
Yes, I kind of cocked my head like my dog when you state knurling. Burnishing also increases the surface density of the dimension being burnished while reducing the finish rms.


My experience with burnishing is in an industrial environment where a diamond tool with a polished radius is preloaded onto a surface to burnish proximity probe diameters on more expensive rotating equipment. typically the diameter has already been ground to a total TIR of .0002 RO concentric with the bearing fits. It is used to measure a vibration function call displacement. Outside of that I have no other experience.