Because nickle plating isn't as durable as you might think, you do need to be careful about how often you do a detail cleaning of the cylinder face.
There are two methods that don't damage the finish.
First is the "lead-away" cloth. This is a treated cloth that just wipes the carbon and lead off by rubbing the area.
The second is one of the carbon cutter chemicals that is applied to the area and allowed to work.
You can buy lead-away cloths at most gun stores under several brand names. You can buy carbon cutter chemicals from some gun stores and from Brownell's.
I don't recommend using any metal polishes, even fine ones like Flitz, because they ARE abrasive and will remove the plating if used too hard or to often.
Again, I wouldn't clean the cylinder face more often then absolutely necessary to limit wear of the finish.
Cleaning the face often just to make it look nice will accelerate wear of the nickel.