Got carbon accumulation on my gas piston and inside the flash suppressor.   After soaking in Hoppes #9 and KG-1, elbow grease with soft metal brushes & fine steel wool, it's not coming off.   Would Slip 2000 Carbon Killer work any better?

MPro-7

The carbon buildup inside the LID of my suppressor was tough, but it got it done. Brass brush is mangled.

Spray with a carb cleaner or gun scrubber then hit it with a brass brush - if no corrosion etc. dont worry about it.

I had fits trying to get carbon out of my AK-74 chrome lined muzzle brake.
I tried soaking with Hoppe's #9 and Slip 2000 Carbon Killer with very poor results with either.
I packed the brake full of paper towel and liberally soaked the paper towel then let it stand, sometimes for several days but the brake and gas block were still black.

One day I was out of Hoppe's so I tried Shooter's Choice Extra Strong Copper Remover.
I was amazed that the carbon was removed down to the hard chrome quickly.
I used some inside the chrome lined gas block with the same excellent results, so that's what I use.

Try spraying it heavy with some Ballistol and let it sit for a while.  Hit it with a good brush (optional) should clean right up.
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I did this with a stripped ar bolt,  put the pieces in a "solo" cup and sprayed it good with ballistol let it sit overnight.   Actually, just rinsed it off with steaming hot water the next day and it was clean, very clean. Not a bit of carbon left on it, the bottom of the cup looked like you drained some well used oil...nasty black mess.

I’ve actually had great results with Balistol too on carbon.  I use green nylon pads on chromed gas pistons.

Thanks I have some Balistol will try it