Go to your dentist and ask if they have any old dental pick that they use for cleaning teeth. They work excellent for picking carbon off.
You can actually buy these at Princess Auto in a couple of different flavours. Guys working with hydraulics use them for pulling out o-rings. About $5 for a pack of 4 different styles, IIRC. Not the greatest quality steel, but they'll do.
I go through a fair number since I need to have them on hand to give out to our guys on remote sites for use when replacing fiddly little o-rings in breathing air lines. Last time I was in, Princess also had a better quality version available with a longer shaft and a knurled anodized aluminum handle for better grip and leverage.
+1 on the Break-Free CLP. I used it a lot in the CF, and I use it as a cleaner with my own guns. When used in combination with a (relatively) soft metal bristled brush, it works wonders. Especially if you give it a bit of time to soak into and soften the carbon.
If you really want to get something super clean:
1. Clean it with CLP and regular brushes/picks/tools.
2. Give it a really good soaking with CLP and let it sit for a week.
3. Clean it again. You'll find that any leftover carbon is now super-soft and comes off pretty easily.
4. Use the brake/carb cleaner...just don't forget to do so in a well ventilated area. This will remove any last vestiges of carbon lurking dissolved in the CLP film on the metal.
5. Don't forget to protect it with some good quality gun oil (or just CLP) after degreasing with that brake/carb cleaner. After degreasing, your gun doesn't have much protection from moisture. What's the point of cleaning it if you leave it vulnerable to corrosion?
Yeah...that method is a lot of work. Far more than most people want or need to invest. The only real reason to want your gun to be that clean is because you WANT your gun to be that clean. I guess the urge to get every last speck of carbon off of certain parts of an AR can be difficult to get rid of once it's been implanted
