Does anyone know what diameter the gas ports on a beretta 301 3" mag shotgun are supposed to be? I just bought one and it's not cycling on 3 dram 1 1/8 ounce target rounds, but it's fine on the 3" hunting rounds. I've already stripped, cleaned and lubed the entire gun(including the recoil buffer spring) and it didn't help. I suspect hard deposits in the ports(I poked a wire through them to clean them) but I don't want to accidently bore them out too big. Help please!