Was in HD again the other day browsing around the seasonal aisle. I spotted a Rutland round 6" Poly brush and brought it home. Something like $15. I was surprised at how hard and rigid the brush is. Anyhow, I wanted to do a test run on some extra length of my 6" liner before I attempt a sweep in a month. The brush definitely fits snug and makes a scraping sound while pushed and an even louder scraping sound when being pulled. Is this typical? After pulling it out I checked the liner to see if it scraped it. It didn't. Also, I tried twisting the brush a little while inserted. Didn't seem it wanted to do that. I'm going to guess that poly brushes aren't supposed to function like a soot-eater, yes?