I was not going to jump in on this but I think a lot of shooters are missing a point. Copper is not the problem, copper fouling is not the problem. The problem is "CARBON" fouling. We, in the short range precision shooting, went through the moly stuff 25 years ago and it faded out very quickly. The wheel came back around about 5 years ago and again it has faded out. The idea of moly and that other stuff Danzac or whatever was to prevent copper fouling. How does copper fouling start, Think Galling! What is galling? two like metals rubbing together. All barrels have cracks, roughness, whatever. The first bullets go down the barrel and some of this roughness picks up copper off of the bullet jacket the next bullet goes down the barrel now you have a like metal, under pressure rubbing aganist it's selve, galling, which translates into copper fouling. The main difference between barrels is the amount of roughness. Now the more you shoot the barrel the more roughness you will get because of the extremely high temperatures of the burning powder which causes the metal to deterioate and crack. Look through a borescope after a 1000 rounds and it will scare you. Now what happens is that the metal where the heat is, normally from the case month to about 12" up, depending if you have a thunder boomer or a .222 actually cracks inward, this is has been proven with air gauges. Now what do the cracks do? pick up copper, what does the copper do? picks up more copper through galling. Therefore under normal circumstances the older the barrel the more it will foul. Now moly is suppose to help that situation by slowing down the amount of galling because in fact it is a lubricate. But the problem now is what about the carbon fouling? Everytime you burn powder or most things it leaves a residue. In the case of powder it leaves carbon in that first 12". carbon is hard and it will build up to the point of actually swaging the bullet as it enters the barrel after firing. Example, and I will use extreme numbers here to illustrate only. You have a barrel that measures .308 and you go shooting, after a 1000 rounds without cleaning the carbon out now the first 12" of that barrel now measure .300 when you fire the next bullet that bullet is swaged down to .300 then goes through the rest of that .308 barrel, get the point, this is not a good thing. What I do is to get a solvent such as TM Solution which is a proven carbon remover, run two very wet patches down the barrel, short stroking the second patch in that 12", let sit for 5 minuets and patch out. If you want to use a solvent after that thats your call. Does it take out moly, don't know, I do not use moly or anything else for that matter, although I have tried them. Now I know that a bunch of you people are going to jump in with science and grammar in the above deal so have at it.
Bill