Hunting Arms and Ammunition: Rifles
The Purpose of the Hunting Rifle
Many types of game animals are hunted with rifles. In every case, the hunter’s objective is to make a quick, clean kill. Shot placement is the most important consideration in reaching that objective. Three major systems form the vital areas for animals, the central nervous system (the brain and spinal cord), the cardiovascular system (the heart and major blood vessels), and the pulmonary system (the lungs). Severe damage to any of these systems results in rapid, sometimes instantaneous death. Damage to the skeleton, large muscles or the digestive system may cause the animal to die, but these are not prime locations for shot placement. Knowing the vital areas and placing shots in them is a basic responsibility for the hunter.
Rifles fire a single projectile. The bullet kills by transferring the kinetic energy of the moving bullet to the vital areas of the animal. As that energy is transferred, it creates a powerful hydrostatic shock. Shock is caused by fluids (water) in the animal’s tissues moving violently away from the area around the bullet as it passes through. Let’s demonstrate how that works. Put your eye and ear protection on and watch the two-gallon oilcan sitting near the 100-yard target frame. What happened? The energy in the moving bullet was transferred to the water. The water moved away from the impact area so quickly that the can seemed to explode. Since animal tissues are mostly water and their bodies act as a containment vessel, a hit by a bullet causes similar results. A well-placed bullet of adequate energy will kill an animal quickly and cleanly. Putting it in a vital area is the key.
Bullet Energy, Momentum and Recoil
Bullet energy is commonly expressed in foot-pounds. The impact of one foot pound is about the same as dropping a one-pound can of beans from the height of one foot. The smallest cartridge normally used afield while hunting is the .22 rimfire cartridge to be adequate for hunting small game animals, like squirrels, rabbits and raccoons and smaller varmints up to about the size of a woodchuck or a fox at close ranges. Put your eye and ear protection back on and watch the bar of soap on the stand. (Note: soft soaps will usually open up along the “wound channel” but hard soaps may seem top shatter into small chunks.) Even though this bullet is capable of killing animals as large as a steer at close range, most hunters will not use them for any animal larger than those listed here.
On the other end of the energy scale is the most powerful U.S. made sporting rifle cartridge, the .460 Weatherby Magnum. This rifle is intended for use on large, dangerous game like elephants, African buffalo and the biggest bears. It fires a heavy bullet at muzzle energies of about 7000 foot-pounds. Compare the .22 long rifle case and the belted magnum centerfire case being passed around. It is easy to see that much, much more propellant (powder) can be loaded in the larger case. Sending a great deal of bullet energy and momentum down range also has a negative side. One of Newton’s laws says that for every action there is an equal and opposite reaction. Thus, the momentum of the bullet at the muzzle (mass times velocity) results in a recoil sensation that is equal. Fortunately, the mass of the rifle and the shooter is much greater than the mass of the bullet. Big bore rifles still produce considerable felt recoil, and that recoil sensation is a significant consideration for selecting a hunting rifle. A shooter must be able to tolerate the recoil adequately to fire the rifle enough to learn its characteristics and to shoot accurately. Shot placement is much more important than energy in making clean killing shots.
Choosing a Hunting Rifle
Selecting a hunting rifle often involves striking a compromise among a number of factors. Legal requirements must be considered. The hunting regulations may require a minimum caliber or minimum muzzle energy for some types of game. The type of action may be important to some shooters. Many action types are available today, but personal preferences may dictate the action type before the caliber or chambering is selected. Several modern single shot rifles are available, primarily based on rolling block, falling block or hinge actions. Combination guns on hinge actions are available from one American manufacturer and several European ones. These rifle-shotgun combinations can be very versatile game guns. Some big bore, double rifles for dangerous game also are available. Many riflemen prefer bolt-action rifles, and most rifle cartridges are offered in a bolt-action model by some manufacturer. Lever action rifles are used by many hunters for their speed of operation and handling characteristics in tight cover. The design of some of them, those using tubular magazines for example, dictates the type of bullet that may be used safely. In general, they are more “fussy” about case dimensions and require a more conservative approach to handloading ammunition than to single shot or bolt action rifles. Shooters who use slide action or semi-automatic shotguns may prefer similar designs in rifles. Both designs offer excellent operating speed, but they are available in a more restricted selection of calibers and chamberings than are some other action types.
Personal tastes and aesthetics are also a major factor. Some shooters prefer a particular brand or model of rifle because of its reputation, feel or fit and finish. Others may have a history with a particular model or manufacturer that amounts to tradition. Aesthetics are important. The way you feel about your rifle can have a significant impact on confidence and the level of use as well as the pride of ownership. Of course, cost is also important to the majority of rifle buyers.
Once the questions of legality, style and taste are answered, the shooter needs to address some physical considerations. The intended use of the rifle is vitally important. Bullet mass and velocity affect energy, momentum or penetration, trajectory (the arcing flight path of a bullet), recoil and other factors. Heavier bullets retain their velocity and energy better than lighter ones. They also produce more recoil at similar velocities than do lighter ones. Lighter bullets can be driven to higher velocities without excessive chamber pressures while producing lighter recoil. They tend to shed that energy more quickly, however, and they may be more lightly constructed. The construction will have an impact on both penetration and tissue damage.
Given the option to choose, most big game hunters like a rifle with adequate energy and bullet mass to carry completely through the animal. Although some of the energy in the bullet is “wasted,” the exit wound is likely to be large enough to create a blood trail that is easy to follow if the animal must be tracked for recovery. The hot .22-250 with its muzzle velocity of nearly 4000 feet per second and 55-grain bullet generates energies comparable to the .30-30 with 150-grain bullets. Both of them have adequate retained energy for deer-sized animals out to 150 or 200 yards. The light, fast bullet from the .22-250 will seldom leave an exit wound and entrance wound will leave an insignificant blood trail in most cases. It may even break up on the surface. The heavier, slower .30-30 is more likely to carry its similar energy through the animal, leaving an exit wound and creating a better blood trail to aid in recovery. If, on the other hand, the object of the hunt were woodchucks at 300 yards, the .30-30 with its rainbow-like trajectory is a much poorer choice than the .22-250. The smaller bullet will come apart violently assuring quick kills at long range, and the flat trajectory makes it easier to hit distant targets. Most experienced deer hunters consider the .24 caliber or 6mm chamberings with strongly constructed bullets to be about the minimum for deer.
The intended use of the rifle must be considered carefully. Will it be used as a specialty arm or for a wide variety of game? The assortment of bullet weights and styles has a strong influence on the versatility of a rifle. Rifles in the 6mm to .308 caliber classes have a wide range of bullet types and weights, making them adaptable to species from varmints to big game. Heavier bullets in larger calibers (.277 to .308) are suitable for the largest species in North America. For the one rifle hunter, these make an excellent choice. Specialty rifles can assume part of the versatile rifle’s role and do the job more efficiently. The prairie varmint hunter taking coyotes for their pelts could find a hot .17 caliber rifle or a .222 very useful. Larger calibers would cause more pelt damage. On the other hand, these would not be very useful for black bears or bighorn sheep. A .338 or .375 magnum might be an outstanding choice for moose or coastal grizzly bears, but both of them are gross overkill on whitetail deer or pronghorns.
Rifle selection boils down to a cluster of factors that could be called the normal use of the rifle. Adequate energy for clean kills is essential. Adequate velocity to handle shots that might normally be encountered is also important. This is governed by the species, terrain and hunting methods. The hunter who specializes in whitetail deer in dense cover seldom shoots at a deer over 100 yards away. Flat trajectory is not a critical factor. On the other hand, the pronghorn hunter will find a fast, flat-shooting rifle very helpful on the open prairies and sagebrush flats. If the rifle is to be used in a wide variety of situations, versatility is important. Chamberings like the .308 and .30-06 excel as versatile rifles, as do the .270, 7mms and .30 caliber magnums. If it is to be a specialist, adaptation to the use is a key. Larger animals generally place a premium on penetration, a product of both bullet mass, velocity and bullet construction. Dangerous game calls for overkill within the ability of the shooter to handle the recoil. Action type, model and aesthetics are important to the enjoyment of using the rifle in the field.
Bullet Selection
Bullets commonly are available in diameters from approximately 0.17 to 0.458 inch. These diameters fare known as calibers. They may also be expressed in metric units. Thus, the .243 is a 6mm, the 7mm is a .284 and the .308 is a 7.62mm. Note that sharing a caliber does not mean that the cartridges are interchangeable. In fact, using cartridges other than those specifically designed for the chamber of your rifle is extremely dangerous.
In general, bullet weight or mass increases as caliber increases. The smallest commonly available bullet for .30 caliber rifles is approximately twice the weight of the largest .22 caliber bullet. The amount of powder necessary to drive a bullet at a given velocity generally increases as increasing mass. As explained above, recoil and momentum or penetration increase with mass and velocity, and energy increases with mass and the square of the velocity. Adequate velocity and mass result in adequate penetration and terminal energy.
Bullet construction is also important. Lead alloy bullets or cast bullets may be used at modest velocities. Jacketed bullets have a lead core surrounded (more or less) by a jacket of harder materials, usually a copper alloy. Monolithic bullets are formed from a solid piece of metal. Jacketed or monolithic bullets can be driven at higher velocities than cast lead bullets.
Monolithic bullets or those with full metal jackets are designed for maximum penetration and mass retention. Several other bullets types are designed to retain most of their mass while expanding to kill cleanly. Partition bullets, core bonded bullets, hot-core bullets and bullets with variable jacket thickness are designed for that purpose.
Sectional density is a term applied to the relationship between the diameter or caliber of the bullet and its mass. Within limits imposed by stability, bullets with higher sectional density retain their momentum better than shorter bullets with lower sectional density. This has an impact on both intermediate ballistics, the flight path of the bullet, and terminal ballistics, the penetration and energy transfer of the bullet on impact.
When a shape factor is added to the sectional density, a ballistic coefficient can be calculated for a bullet. This coefficient relates to the “slipperiness” of the bullet through the air. Pointed bullets have a higher ballistic coefficient than blunt ones. Round nosed bullets have a higher coefficient than flat nosed or wadcutter styles. Boat-tailed bullets, bullets with tapered bases, have a higher coefficient than flat based bullets. All of these factors combine to govern velocity retention down range.
Selecting a Hunting Rifle
As you can see, picking a hunting rifle is a little more complex than merely walking into the gun shop with a checkbook and a gleam in your eye. It involves some thought and planning. The next exercise is designed to give you some practice in picking rifles for various uses. Visit each one of the stations. Read the statement on the anticipated use for the rifle and the conditions the hunter expects to encounter. Then select a rifle from the list of options offered. Give your reasons for selecting that rifle and the reason for rejecting the others. Make them personal and try to be realistic in your selections.
