iv'e had problems with the cheaper kind of ammo. if you look at the primers closely in the cheaper ammo, the shell has a variacne in the primer depth. were you having intermitten shell firing? fiochi shells are not the best. hunting shells i would use a high brass remington express shell. for target sts remington are good. double A are a good choice also. with the quality of benelli guns the problem is most likely not in the gun.