My new Citori misfires the bottom barrel..It is strange because the shell is clearly marked where the pin hit the primer but will not fire..I tried several different shells and the same result.I used it in Dec on a quail hunt and it worked fine...then again in jan and feb at a sporting clay event... Then 2 weeks ago used it at a fundraiser for the first 10 shells and it worked fine..Then went bad.... Any ideas..??

Clean the crap out of it. Firing pin sounds like it's gummed up.

Here is a good thread on Shotgunworld.

Citori Receiver Maintenance

Look at the pin, it's possible it's chipped from shooting ammo with especially hard primers, Citoris are notorious for it

One of the guys in my college trap and skeet club had this same issue; unfortunately this happened while we were shooting at the college nationals.

His gun was light striking primers because of excessive fouling/residue in the action and luckily there was a gunsmith onsite to fix the problem; the gunsmith performed the same servicing as depicted in the link above that 5 Stand Dan posted.

His parting words to us were..... "And that will teach you youngsters to have your guns serviced well before coming to a national shoot!"

Trade it in on a SxS, they don't have the issue of less mechanical advantage on the bottom vs the top.