Or just use this for a quick clean in the field..much cheaper
Snake Rope Brush Bore Cleaner Tool G01 : 12 GA Gauge - m.tmart.com
Shotguns tend to get plastic fouling from the wads. No FMJ slugs are going to take that out.Pro tip. If you never use raw lead projectiles or corrosive ammo you never need to clean your barrel. If you do use raw lead just shoot a couple of fmjs through the barrel and it's clean.
If the barrel is leaded, all you're going to do is make it harder to properly clean.