If it's 12 gauge, take a dime and try to put it in the muzzle, make sure it is unloaded first, if the dime goes halfway in or more, especially all the way in, your chokes are prolly mod. or more open like I.C. or Cyl. Some folks say that you can shoot slugs with full choke anyways, but i prefer something a little more open. This dime test also work for determining constriction for steel shot compatibility. When I was much younger I would check other young folks barrels for them and ask them for a dime to use, I'd check the choke and keep the dime, no one ever asked for it back, and back then a dime was worth a dime!