I'm assuming you are refering to a turkey shoot? Ideally you would use a x-full choke used for turkey hunting, but all the shoots that I ever went to did not allow screw in chokes. So you are looking for a full choke, and the choke is usually stamped on the barrel. If not, you can purchase a choke guage, which is a wedge shaped piece of metal with the guage and chokes stamped on it. Keep in mind, not all guns pattern the same with the same shell. So even getting a full choke is still subject to the luck of the bb.