Varmint rifle
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Varmint rifle is an American English term for a relatively small-caliber firearm (or even a high-powered air gun) primarily used for varmint hunting—killing animals such as coyotes and other vermin considered to be farm pests.
The varmint gun fills a design gap between small game rifles and rimfire firearms. .22LR (the most popular rimfire caliber) is somewhat underpowered for small predators, but is perfectly adequate to dealing with typical vermin; the term "varmint" covers larger animals which usually harass farms from the outside (as opposed to infestation by vermin), and the varmint gun assists in the control of them.
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[edit] Common design elements
While any rifle of sufficient power can be used to dispatch targets of opportunity (the venerable .30-30 Winchester lever action and the Ruger Mini-14 are common truck guns or ranch guns kept handy for this) the deliberate taking of varmints requires special characteristics more common to target rifles than "normal" hunting rifles.
[edit] General characteristics
Varmint rifles can typically be distinguished from other light-caliber hunting or plinking rifles in the use of heavier barrels and (often) omission of open sights. Use of magnifying optics allows for more accurate fire (often on very small, distant moving targets), and heavier barrels are both more accurate, and allow the user take more shots in any given period of time before barrel heating can reduce accuracy. Barrels will generally be free-floated, and other accurizing techniques will be performed (either by the manufacturer or the owner). The stocks will generally have wider forends, designed for use on stable sandbag rests, and high combs for easy use with optics.
Since part of the definition of a "varmint" is that it is a nuisance, varmints are not stalked, but rather they are hunted from a fixed position. This makes weight of little consideration in a varmint rifle, so heavy barrels are common. Varmints are also not subject to the same bag limits as game animals are, so far more shots may be fired. The heavier barrel is, in general, more accurate than a light barrel, plus the extra mass helps reduce the felt recoil and absorb the heat from more shots before expanding and potentially reducing accuracy. Folding shooting benches and sandbag rests help provide a stable base for the shooter, allowing the maximum accuracy to be extracted from the rifle.
[edit] Calibers
Since varmints are generally smaller animals, large, heavy bullets are not needed. A light, fast bullet gives a flat trajectory, making range estimation less vital for accurate shot placement. Smaller bullets also produce less noise that might scare the target animal. .25 caliber (6.5 mm) and smaller rounds are most often used for specialized varmint rifles, with .22 caliber (5.56 mm) and .24 caliber (6 mm) rounds being the most common. In years past, the .222 Remington and .218 Bee were popular varmint rounds, but newer, higher velocity rounds have rendered them all but obsolete. Calibers such as .223 Remington, .22-250, .220 Swift, .243 Winchester, 6mm Remington and .25-06 Remington are common, .22 Hornet is getting a significant following again for its much lower noise, though varmint rifles tend to be chambered in a wide variety of cartridges, and wildcat cartridges are quite common (the .22-250 and .25-06 got their start as wildcats). Varmint shooting is one of the few areas where calibers smaller than .22 (5.56 mm) are found; the .17 Remington and various other .17 caliber (4.5 mm) wildcats have a vocal following, and the new .204 Ruger is well suited to varminting, and may be the first in a new line of .20 caliber (5mm) rounds.
Velocities for modern varmint rounds are generally high, well over 3000 feet per second (955 m/s) with some rounds reaching 4500 feet per second (1430 m/s). This allows long range shots with a short time of flight, and little change in trajectory at different ranges (see external ballistics). A bullet drop of only a couple of inches (about 5 cm) is enough to cause a miss on smaller varmint animals, so accurate range estimation and flat trajectories are a must for clean kills at long ranges. Popular shorter range calibers (for ranges less than about 100 yards (100 meters)) are .22 Magnum and .17 Hornady Magnum Rimfire, with the new .17 Mach 2 offering promising ballistics. The .22 Long Rifle will also do, but the low muzzle velocities result in a supersonic to subsonic transition on the way to the target, which can negatively impact accuracy.
[edit] Action types
Bolt action rifles dominate the class, with a few specialized AR-15 variants and single shot rifles making up the rest. Most bolt action rifles, if accurized, can be successfully used for varmint hunting. While nearly all varmint guns are rifles, there are a few pistols, generally single shot and bolt action pistols in rifle calibers such as those developed for metallic silhouette shooting, that have sufficient accuracy, range, and trajectory to allow them to be used for varmint shooting. The Remington XP-100 bolt action pistol and it's aptly named .221 Fireball cartridge, introduced in 1963, were developed for varmint hunting; the full name is the "Model XP-100 Varmint Special".
For varmint and pest control in urban areas, air guns make suitable choices. While the limited power of an air rifle (generally far less than a .22 Long Rifle) limits its usefulness to small rodents at very short range, the limited penetration and low noise allows them to be used in areas where use of firearms is illegal or impractical. The popular air gun sport of field target is based on small game and varmint shooting, with targets often shaped like rabbits, squirrels, and other suitable small varmints. The low velocities of air gun pellets makes accurate range estimation paramount, so high magnification telescopic sights are used, with calibrated focus knobs that serve to estimate the range.
