I don't spray any oil on the breech plug or the flash channel when I clean the gun. The only lube is Knight plug grease on the threads. perhaps oil in the flash channel is a culprit. I haven't seen the buildup you talk about with BH209. Last time I shot BH209 in the Encore the pressure to load after the 1st shot was a real bear!!! I had not cleaned the oil out of the barrel before I loaded the 1st shot. I think oil reacts with BH209 causing crud. This loading difficulty was not experienced on my prior outing where I wiped the barrel out prior to loading.