CLR? Ehhh. It'll work but it's a bit much. The best I've tried recently has been from Modern Spartan Systems, their Carbon Destroyer is really kickbutt. Coach and I used it on all of our guns with great results and we weren't overly impressed, it was good but we didn't see anything special on those. But, then we picked up the Trapdoor Springfield which was deeply covered in carbon and with a lot of carbon in places where we couldn't really get to it. A quick swipe of CD and it just ran off. Coach is persnickety about his Trapdoor and he went plain ol' gaga over how clean I got it in just 10 minutes of not even scrubbing.