[spunkets]

"a brass brush"

Brass is softer than steel. It's used, because it won't scratch. Polishing powder, or compound is used. Some ammonia containing bore cleaners will pit the metal enough to change the characteristics. That kind of solvent will likely ruin the barrel though in the wrong hands.

[Free Trapper]

Yeah,I know brass is softer but at one time I had friend,"firearms expert" that I trusted and was with a state investigative bureau,tell me a brass brush was enough to change the groove markings to the point of not being able to positively match bullets.

He could be wrong but I questioned him on it and he stood by it.