Extra Barrels or Variable Choke
By referring to the chart it will be noted that the same gun can be used on various game under varying conditions by changing from one barrel to another of different choke and length. On all Browning automatic shotguns, barrels of the same gauge and model are readily interchangeable. Thus a duck gun can become a skeet gun, or a fine upland game gun, by changing barrels.
Versatility of a gun can also be increased by having one of the several good variable choke devices installed on the end of the barrel. Such a device permits the shooter to switch from one choke to another as shooting conditions require. The resulting patterns, although possibly not quite as good, approximate the desired choke for most purposes. However, one should expect the balance of his gun to be slightly upset because of the added weight of the choking device. It is popular today to use screw in chokes. By simply changing the tube at the end of the barrel , you can carry all the different chokes in one pocket.