of the projectile that is fired. For example, a shotgun is called "12-gauge" because a lead sphere that just fits the inside diameter of the barrel weighs . This measurement comes from the time when early cannons were designated in a similar manner—a "12 pounder" would be a cannon that fired a cannonball; inversely, an individual "12-gauge" shot would in fact be a pounder. Thus, a 10-gauge shotgun has a larger-diameter barrel than a 12-gauge shotgun, which has a larger-diameter barrel than a 20-gauge shotgun, and so forth. The most popular shotgun gauge by far is 12-gauge. The larger 10-gauge, once popular for hunting larger birds such as goose and turkey, is on the decline with the advent of the longer, "magnum" 12-gauge shells, which offer similar performance. The mid-size 20-gauge is also a very popular chambering for smaller-framed shooters who favor its reduced recoil, those hunting smaller game, and experienced trap and skeet shooters who like the additional challenge of hitting their targets with a smaller shot charge. Other less-common, but commercially available gauges are 16 and 28. Several other gauges may be encountered but are considered obsolete. The 4, 8, 24, and 32 gauge guns are collector items. There are also some shotguns measured by diameter, rather than gauge. These are the .410 (10.4mm), .380 (9mm), and .22 (5.5mm); these are correctly called ".410 bore", not ".410-gauge". The .410 bore is the smallest shotgun size which is widely available commercially in the United States. For size comparison purposes, the .410, when measured by gauge, would be around 67- or 68-gauge (it is 67.62-gauge), The .410 is often mistakenly assigned 36-gauge. The 36 gauge had a 0.506" bore. Reloading components are still available. Other calibers Snake shot (AKA: bird shot, rat shot, and dust shot) refers to handgun and rifle cartridges loaded with small lead shot. Snake shot is generally used for shooting at snakes, rodents, birds, and other pest at very close range. The most common snake shot cartridges are .22 Long Rifle, .22 Magnum, .38 Special, 9×19mm Luger, .40 Smith & Wesson, .44 Special, .45 ACP, and .45 Colt. Commonly used by hikers, backpackers and campers, snake shot is ideally suited for use in revolvers and derringers, chambered for .38 Special and .357 Magnum. Snake shot may not cycle properly in semi-automatic pistols. Rifles specifically made to fire .22 caliber snake shot are also commonly used by