Gianluca.....Start shooting at least 10 shot groups. Sometimes groups start to open up due to fouling or bedding problems after 5-7 shots. You need to know if this is going to happen, and if it does, what you are going to do to fix the problem. Cheers Paul
Theoretically fouling in the barrel do not accumulate in the event that no shot wad or filler, because i clean up at the bottom of the barrel with a patch wet and then dry.
When i use wad and filler there is a problem, why do not you ever clean the part of the barrel where there is powder, so every 15 shots with the brush wand to eliminate incrustations.