targets generally have even shorter barrels. Small game shotguns, for hunting game like rabbits and squirrels, or shotguns for use with buckshot for deer, are often . Shotguns intended for all-round hunting are a compromise, but a barrel pump-action 12-gauge shotgun with a modified choke can serve admirably for use as one gun intended for general all-round hunting of small-game such as quails, rabbits, pheasants, doves, and squirrels in semi-open wooded or farmland areas in many parts of the eastern US (Kentucky, Indiana, Tennessee) where dense brush is less of a hindrance and the ability to have more reach is important. For hunting in dense brush, shorter barrel lengths are often preferred when hunting the same types of game. Caliber conversion sleeves Shotguns are well suited for the use of caliber conversion sleeves, allowing most single- and double-barrel shotguns to fire a wide range of ammunition. The X Caliber system consists of eight adapter sleeves that allow the 12-gauge models to fire: .380 ACP, 9mm Luger, .38 Special, .357 Magnum, .40 S&W, .44 Special, .44 Magnum, .45 ACP, .45 Long Colt, .410 gauge and 20-gauge ammunition. The X caliber 12-gauge adapter sleeves also come in .22 Long Rifle, .223 Remington, 7.62x39mm and .308 Winchester as well. They even make four adapter sleeves that allow the 20-gauge models to fire: 9mm Luger, .38 Special, .357 Magnum, .45 ACP, .45 Long Colt, and .410 gauge ammunition. Ammunition The extremely large caliber of shotgun shells has led to a wide variety of different ammunition. Shotshells are the most commonly used round, filled with lead or lead substitute pellets. Of this general class, the most common subset is birdshot, which uses a large number (from dozens to hundreds) of small pellets, meant to create a wide "kill spread" to hunt birds in flight. Shot shells are described by the size and number of the pellets within, and numbered in reverse order (the smaller the number, the bigger the pellet size, similar to bore gauge). Size nine (#9) shot is the smallest size normally used for hunting and is used on small upland game birds such as dove and quail. Larger sizes are used for hunting larger upland game birds and waterfowl. Buckshot is similar to but larger than birdshot, and was originally designed for hunting larger game, such as deer (hence the name). While the advent of new, more accurate slug technologies is making