This post is old now, but if there is a leading issue, I've been trying out Sharp Shoot-R's
No-Lead product and found it very effective. It's the first true lead solvent that doesn't involve chemicals dangerous to the steel. Turns lead to a sort black crusty stuff that patches out. No brushes needed.
I agree the Otis system is better than a Bore Snake. I've seen too many stories of people sticking the latter tool in a barrel and having to go through quite a lot of trouble to get them out. Now that I have a borescope, I pretty much try to avoid brushes altogether. You often can see marks, particularly in softer steel like .22 rimfire barrels. Sharp Shoot-R, who makes the lead cleaner, specializes in cleaners that let you patch everything out. They make
Wipe Out, which is available as a foam that works well on copper fouling.
Boretech Eliminator is also very, very good. It's not a foam, but it's a water-based chemistry that attacks copper and carbon very effectively and even gets the tin in lead alloys, weakening them. It attacks copper so fast you will blue your patch if you use a brass jag, so a stainless, nickel-plated, plastic, or special alloy (Boretech sells them) is required that won't react with it. Eliminator is non-toxic and the first nearly truly odorless cleaner that works on everything. Absolutely no trace of ammonia. That it is water-based makes it perfect when you inadvertently acquire corrosive primers. It has corrosion inhibitors so that you can let it dry out in a bore without causing rust.
I also like Gunzilla as a CLP. I always have it or some Ed's Red with me at the range these days. I use a patch in the Otis kit for Ed's Red or I use the small pump spray dispenser of Gunzilla to wet a bore at the end of the range session. When I get home, the carbon has been kept soft rather than allowed to harden, so cleaning is quick with whatever other product I might use. Gunzilla is vegetable oil-based and is also non-toxic and the odor isn't strong or offensive. It dries to leave a lubricating varnish-like layer behind that dust doesn't stick to. Apparently our troops have found it very effective in the sandbox at preventing guns from jamming. It turns carbon into sludge that just patches out.