JapChester 1873 barrel

I have this trapper rifle w/ 16 inch barrel in 45 Colt.

I shoot a Accurate Molds number 454260F boolit ahead of 35 to 40 grains of old E 3F black powder.

Question is concerning this barrel;

I can shoot 30 to 40 of these loads and the fouling is absolutely the cleanest fouling I have ever seen in shooting black powder all these years. I mean it looks almost as clean as shooting Unique powder.

Just wondered if anyone has heard of this phenomenal clean fouling.

Just trying to try to figure out why this barrel of all my barrels shooting black powder ... is so clean.

What is the matter with you Ted? You were warned and should have knocked it off.