Pedersoli's have a patent breech that is quite narrow and hard to clean. As mentioned in the other posts, it is likely that moisture or oil is in the breech area and contaminating any powder charge. When i clean my Pedersoli's, that I can't take the barrel off for flushing, I use a .22 caliber bronze cleaning brush with a patch wrapped around it to get down into the breech area to dry out any residue oil or water. The air compressor can be your best friend when available, otherwise, an alcohol soaked patch will do the trick while in the field,