Wo.
I get everything out of my barrel by
1. pushing Hoppes' #9 wet patches
stretched over a 12 gauge brush through until most of the gunk is out.
2. Then I brush vigourously.
3. Then I repeat step 1.
4. Then I clean the rest of the gun(s). Or just wait as long as I can.
5. Then I do step 2., followed by step 1., followed by a dry patch and an oily patch when clean.
On the other hand, I'd bet on Dave McC's advice over mine.
Regards