The solution you're refering to is called M.A.P. which of course stands for Murphy's oil soap, Alcohol, and Peroxide. I do not go quite as strong on the Murphy's oil soap when I make it. I do more of a 20% - 40% - 40% . Remember, when you use peroxide it can cause flash rusting so make sure you get some oil in that barrel ASAP.

Another solution is 50/50 alcohol and car windshield washer fluid.

Lets not forget good old hot water with a little dish washing soap. It has cleaned off more black powder then all the others combined probably.

Some people use Moose Milk for cleaning. I make a moose milk but use it to lube patches when shooting roundball. I never have used it to swab or clean.