barrel polishing..

[nervoustrig]

There will necessarily be some softening of sharp features like the outside corners of the lands, though on a scale that is so small as to be academic. But to the extent it does, it can be just as easily regarded as a good thing. Rifling need only impart a spin, not engrave a specific profile. For example, consider the various blunted rifling profiles like polygonal and FX Smooth Twist which are quite successful in their own right.

 

[Firewalker]

The intention is to remove miniscule amounts of metal - think of it as the undesirable debris left from any machining operation. To that end, you use abrasives which are so mild that actual, destructive, damage is pretty much out of the question.

GsT

I use medium grit lapping compound and do remove metal with great affect.

No tooling leaves a fine finished surface, chatter, harmonic oscillations in tooling will leave unwanted ridges, burrs etc on the surface. Reducing the friction across these surfaces causes less galling and less sloughing of metals.

Removal of knife edges on rifling is not a bad thing, pellets and slugs conform better to a smooth surface than the serrated-like edge a sharp land shoulder provides.