I hope your new barrel is the way it should be. Put that borescope in again and post some pics please and let us know.
That said, I was cleaning my 1997 41 the other day that I bought used a couple of years ago, it is a gorgeous pristine gun looking as new. After cleaning I too saw an area with my naked eye that did not come clean. Used everything solvent wise, 100+ brush strokes, nada. Then I bought a borescope to take a closer look. Think your barrel is bad? What you see here is the aftermath of a very dull cutter and or chip load in the cutter. It is atrocious to say the least. Same with yours, that is poor rifling, not leading, not heat cracking, shoddy workmanship. The lands are not to bad but the grooves, holy smokes!
I then borescoped my 1965 41, 7 and 5" barrels as well as another 5.5" barrel I recently bought on GB. They were beautiful, shiny, smooth, perfect.
So I called S&W, they sent me a return label. I also talked to several respected smiths and they both said the same thing, poor tooling. I also found a bullseye smith 2 hours from me that specializes in relining that meets bullseye accuracy. So I debated, him for $350 and 8 weeks shop time (he's very busy) or send to S&W and roll the dice. Side note; I sent S&W a 29-2 a few years ago for cylinder lockup issues, paid $150, locked up again on the 3rd shot! So I educated myself and fixed it myself and it works perfect. Strike 1.
My decision? I sent it to the renowned smith for relining. Note, the gun did shoot pretty well, however, I think this needs to addressed.
Enjoy the pictures! Nothing like I've ever seen in my 66 years! And it's the entire barrel too.
Video link too:
Model 41_x264.mp4 - Google Drive