The Shotgun Choke
As any shotgunner knows the choke at the end of the shotgun barrel determines the size and density of the pattern that the shot will produce. Different types of hunting require different shot sizes and choke constrictions, depending on the size of the game and the general range of the target.
In the past, hunters had the option of either buying a different barrel for each choke constriction (Full, Modified, Improved Cylinder, etc.) or having an adjustable Polychoke type device attached to the end of their barrel. Most shotguns coming out of the factories today are equipped with modern screw-in shotgun choke tubes which screw into the internally threaded muzzle end of the barrel. This gives the hunter/trap/skeet shooter the ability to change the choke of the barrel by simply screwing out one choke and screwing in another. No more need to buy multiple barrels. All that is needed is an assortment of choke tubes which can easily be changed in less than a minute when conditions require it.
There are thousands of shotguns out there with plain barrels that can be threaded to accept the new screw-in choke tubes for less than the price of one new barrel. Once your barrel is threaded to accept choke tubes, you will have the ability to pursue any type of game that you may be interested in. Your newly threaded barrel will accept flush lead shot choke tubes, extended length steel shot choke tubes, extended length, extremely tight turkey choke tubes, ported choke tubes in every configuration, Sporting Clays tubes which are extended length with the external portion being knurled for quicker installation and removal, and rifled slug tubes, to name a few. Pretty much anything you want to hunt, you will now be able to hunt with one shotgun.