Take a close look at the labels on both carb and brake cleaners to see what ingredients are present. Many contain chemicals like acetone and toluene which will melt plastic and ruin finishes. I don't remember the name of them, but several of the various barrel cleaning sprays contain 1,1,1 trichloroethane which is a great degreaser that is a lot less hash than acetone. Not all brake cleaners use this chemical, but Brakleen in the red can does, and it's cheaper than gun products. I'll take an old coffee can and stand the muzzle in it, then use the straw to spray the cleaner into the chamber until it runs clear out of the muzzle. This gets the heavy stuff out and then I clean as normal. I mostly do this with dirty .22's and after shooting cast boolits that are lubed with my lithium grease/beeswax lube. The cleaner that runs into the coffee can, just leave the lid off until it evaporates.
This is where I state my opinion about chlorinated solvents. Would it be bad if hairspray and deodorant were still charges with freon, sure but it hasn't been for a very long time. They've even changed all of the refrigerants in our cars and our home cooling systems. There are different levels of badness concerning chlorinated solvents. Think about it, they banned my grandmothers Aquanet hairspray back in the 1970's and Brakleen is still on the market. Progress is a great thing, but as long as we're all driving gasoline powered cars and our home's electricity is powered by burning hydrocarbon fuels we still have a long way to go. The average driver in the USA drives 20,000 miles a year which burns up to 1,000 gallons of gas; multiply that by over 200,000,000 drivers and Americans probably burn 200,000,000,000 gallons of gasoline a year. If the chlorinated solvent in Brakleen isn't harmfull enough to be banned or regulated, I really don't think that my using a couple of cans a year will cause much harm, unless it's poured on the ground and enters the water table. The best way to handle these chemicals is to let it evaporate.