I think break or carburetor cleaners are way too corrosive...
Personally, I use "Shooters Choice" products for 99% of my cleaning...and if I get a real stubborn spot, a little bit of Barnes CR-10 ---but I think the solution to the problem is more like BiDinFL advised...some pipe cleaners, Qtips ...and just clean it after every range trip .../ so you don't get that heavy buildup .....
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