I think the flute brush is a must. Look at E&L Manufacturing. They have a nice chamber face package complete with rod + brush for inside the receiver.
If was only getting one, it would be the chamber face brush. On 223 one can make do with a USGI chamber brush and use the steel brush part for the locking lugs to do some of the cleaning, however, the "HK" face brush being larger still works better.At about $25 each, are the HK barrel flute brush, chamber face brush, and receiver/mag brush worth it? Recommended? Has someone found cheaper or better brushes?