I tried APP powder in several TC guns including Triumph and an Omega, I shot it for 2 years and never had a residue problem of any sort. I finally decided to give up on it as it was difficult to measure with a volume measure and when it attracted some moisture it was very erratic and I live and shoot on the down wind side of Greers Fairy lake which is a 44 thousand acre lake so the humidity here is high all year round.
Evidently the efficiency of the breach plug makes a difference in the residue as the only powder that is really nasty to clean here is 777 and there are only a few who don't have difficulty with crud ring.