Originally Posted By: eightbore
"CHOKE" means there is choke in the barrel. The lack of that mark means there is no choke in that barrel. My 28 gauge is cylinder and improved cylinder by micrometer. It has one barrel marked "CHOKE"


That appears to be the case under Belgian proof rules. Under British proof rules, the lack of the "choke" stamp doesn't necessarily mean cylinder bore, but it does mean not much choke. There might be as much as .007 constriction in a British barrel without the "choke" stamp.