Alan: It depends on how you define "fouling". For light lead or copper fouling, I find that SHOOTER's CHOICE works well. However, after using it for over 65 years, I am also addicted to the odor given off by Hoppes #9, which to me is kinda like Love Potion #9. Fouling can be Lead, Copper, Plastic (shotgun wads), or even Zinc (in extremely light-for-caliber bullets).
Ammonia laden beverages such as Sweet's will remove copper quickly... it will also damage your bore if left in too long.
The absolute best way to remove LEAD is the Lewis Lead Remover system (available from ,Brownells.com and/or Midway-USA.com. It requires the most work, but it is the most effective and takes less time overall. This system will also remove plastic from wads, but is not as good for copper. This system only works on barrels 9mm~.45ACP and up to 6~8".
Another very effective way to remove LEAD and ZINC is the method of electrolysis, as found in the OUTER'S LEAD OUT system. This system consist's of a long rod you put down a plugged breach and a special liquid that acts as an electrolyte. The rod has rubber grommets that prevent it from actually touching the barrel (all supplied in various calibers) . The rod is then connected via clamps and wires to a unit that you plug into your 120 volt outlet. While you relax on the rear deck ad drink a beer, the electrolysis works and the lead/zinc, (and copper?) all get pulled from your barrel on to the metal rod. This process takes time depending on how bad your barrel is fouled, but it works like a charm... mirror finish guaranteed everytime. When finished, you save the liqiud, and easily wipe the rod clean for reuse. The riubber grommets are also reusable. Hardest part is pouring the correct amount of liquid to fill up the bore from breach to muzzle while the rod and grommets are in place. Works on barrels of any handgun or rifle caliber... can be made to work on some shotguns as well I suppose, if you can scrounge up a rubber plug for your breach and big size grommets (donuts for your rod).
