I have a FNAR and use an Otis cleaning kit on it. I use the same cleaner on it as I do my bolts guns, that being Wipe-Out. It does a nice job on copper. The FNAR with the chrome lined barrel gets very little copper fouling, but the Otis patches do a nice job of cleaning what is there (and of course the powder fouling that accumulates).
Use your Otis kit....it will do the job.