I scrub the bore of a threaded barrel with a Hoppe's soaked bronze brush back and forth about 10-20 times. I then remove the brush and run a dry cloth through it. I repeat this process until the cloth comes out clean. This usually only takes 5-10 reps. A visual inspection of the bore proves that it's very shiny on the inside. At this point I'm confident the bore is clean.
If I do the same with a poly-rifled barrel, it takes about 10-20 reps. Once the cloth starts coming out clean I let it sit and visually check it 5-10 minutes later. Inevitably I see streaks on the inside! I run through bore again with the soaked brush and follow up with more dry wipes and they start coming out dirty again! This ONLY happens with my poly-rifled barrels (USP 45 and P2000sk 40S&W)! The streaks never go away and after I'm a couple hours into it I just have to hang my hat and call it a day. At one point I was worried perhaps my Hoppe's and brushes were dirty so I started with a fresh batch mid-cleaning. I still get the same dirty results.
Ammonia is corrosive and the bottle of CR-10 explains after use to reapply a very thin coat of lube to whatever metal surfaces have been soaked with the agent. Apparently it strips the metal of just about everything and make it very vulnerable to rust. generally I put a couple drops of RemOil on a cloth and run it on the inside and outside of the barrel. Not surprisingly, even after this process I still see streaks inside my poly-rifled barrels.
I just don't feel like my poly-rifled bores are ever truly clean. Truth be told, I am not suffering from any accuracy issues nor any malfunctions or poor performance from either of these weapons, but it is frustrating to know I spend a whole lot more time on these things and they never end up being as clean as the other weapons. No one else experiences this? If not I've got to be doing something wrong, although I can't say what since I seem to clean threaded barrels just fine.
If this boggles your mind, just imagine how I feel....