I am only shooting BH209. I have about 8 different muzzleloaders that the family uses and I like to shoot and sight them in. I have .50's, .45's, stainless and blued. Because my range is outside my basement door this winter my goal is to figure this dirty bore , first shot bore, clean bore ,etc. thing out with my guns. Most these guns are shooting 1" groups @100 yards for comparison.
My shooting procedure is to dry patch, damp patch with 50/50 mix Hoppes #9 and alcohol, then 2-3 dry patches.
Just started noting the data and using this procedure.
Here is what I have found so far.
Dirty bore 25-50 fps slower
Clean bore 25-50 fps faster
If the gun sits loaded the fps seems to change a little.
The bullets are still hitting within an inch.
What I found so far with not a lot of testing is if the gun has sat even clean, I will fire a primer and then clean.
I can also clean and patch after I reload.
Doing this the guns seem to shoot back in the group.
I plan on taking each gun and doing a test over several weeks this winter if the weather permits.