Cayugad
Funny you should mention this.. the last time I shot the U-Mag the primer were sticking something fierce. It was miserable to shoot... Even shooting just the bare primer resulted in a stuck primer. Finally i gave up - pulled the hammer assembly and the breech plug. I ended up flushing it with windex. Cleaning it with a Q tip - the primer pocket that it is and put it back in the gun. Everything then worked just fine...
My speculation... after sitting for almost a year in the safe the BP, the flash channel and the flash hole were plugged with really old oil.. almost like it had thickened and harden in there. I am betting if i poured water down the barrel it would not have made it through the BP...
Like I said though after I cleaned it at the rock pit and reinstalled it - it was like new again...
Some days!!!!????