ABCs of Rifle Shooting

Part I: The Rifles

CHAPTER ONE

An Overview

The rifle and its correct maintenance, use, and employment form the first fundamental component of accurate shooting, and while the rifle may seem to have pride of place as a symbol of a shooter’s skill, it is, in fact, no more or less important than the condition of the shooter and ammunition, with regards to accurate shooting.

In a commercialized world, there is a culture or belief of excess creating success in shooting. Many firearms dealers, gunsmiths, and shooters will tell the shooter that the next newest rifle is undoubtedly the best, and that the only way to learn, improve, and succeed is to open their wallet and spend all that they can on that exotic action, specialized scope, or rare breed of rifle. While this may have been true in the 1960s and ’70s, where custom built rifles were the only way to go to achieve superior performance, modern manufacturing techniques and the use of CNC lathes and mills have allowed firearm manufactures to build good quality firearms not only faster and cheaper, but also more accurately. The off-the-shelf rifles of today are of the same quality as match rifles of yesterday. That said, many rifles made some 20, 30, or even 50 years ago, providing they are without defect, are capable of providing very good accuracy and, in many cases, will outshoot the majority of shooters, when set up correctly and used in conjunction with good quality commercial or handloaded ammunition.

So what does all this mean? It means that the accurate rifle doesn’t have to be the latest and greatest or most expensive. Indeed, the accurate rifle is the rifle that the shooter is willing to put time, effort, and training into, as opposed to pining for what the Joneses have; bear in mind that the Joneses generally believe that the latest and greatest and most expensive rifle will improve their range scores or enable them to take that bull elk. In most cases, it won’t help them to do either.

Take another look at what you have in your rifle cabinet or safe. Now, learn to use what you have, to its limits. Too, clearly define what it is you want to achieve, then pursue a rifle, whether it be factory or custom, that will fulfill your needs. Not only will you save money and put the Joneses to shame, you will improve your skill and knowledge as an accomplished shooter.

THE RIFLE IN OVERVIEW

The typical rifle is comprised of three major components, the action, barrel, and the stock. These three components work in unison and must be treated equally. Any limitation in one particular component will limit the level of accuracy the rifle can achieve.

This is 237 years of firearms evolution, from American independence to the present day.

The principle role of the action is to transfer ammunition from the magazine to the chamber of the barrel and to provide a firing mechanism to the ammunition. It is necessary that the action hold the ammunition in the chamber in line with the center axis of the barrel.

The principle role of the barrel is to contain the explosion inside the ammunition’s case during firing and direct the projectile onto the barrel’s rifling so that the projectile follows the barrel’s center axis as that projectile speeds up and rotates on the rifling to attain stability and leave the muzzle of the barrel (again, evenly and on the same center axis as the barrel).

Finally, the principle role of the stock is to provide the shooter stable points of contact with both the barrel and action, so that the unit as a whole can be held and aimed in a stable manner.

By breaking a rifle down into these components and roles, it becomes easier to see how the components work, what can be done to improve the components, and what conditions need to be provided by the shooter to attain maximum accuracy. In the next several chapters, let’s look at each and all of these facets.

CHAPTER TWO

Barrels

Barrels are made, generally, from 4140 chrome-moly steel or 416 stainless steel, both of which are perfectly suited to the rigors of firing pressures. Bores are drilled using specialized deep drilling equipment, and then the rifling is either button drawn, cut, or hammer-forged into the barrel. From there, the barrel blank is turned again to make it uniform to the bore, and a tenon, chamber, and crown are cut into the blank, readying it for fitting to an action.

There are many different combinations of barrel weight, length, and rifling twist rate, just as there are many styles of rifling itself, in terms of the number of grooves and the angles cut onto the lands. Many of these factors are predetermined by the chosen caliber and usage—terms such as light sporting, varmint, target, etc., come into common use—and this is the manner in which commercial rifles are generally marketed. The only time a shooter will really have a say in terms of the particulars of their barrel is if they’ll be rebarreling an existing action with a custom-made barrel.

There really is very little difference between an off-the-shelf factory barrel and a custom barrel, though final finish and quality control may vary. The edge a custom barrel provides is that it allows the shooter to tailor the barrel to their purpose. For instance, one can use a barrel of greater length to obtain greater velocities, or manipulate the twist rate to stabilize heavier projectiles, all in the pursuit of gaining accuracy over a particular distance or from a particular caliber. That said, for the majority of hunting and competition, factory barrels are sufficient. If the shooter wishes to compete at a high level or participate in extreme-range hunting, then a custom barrel may be appropriate for those intended uses.

INSPECTING AND ASSESSING RIFLE BARRELS IN USE

Whether you plink a few targets a couple times a month (or a couple times a year), are sighting in for a long-awaited hunt, or are on the range every hour your free time permits, you’re going to need to thoroughly and objectively assess the condition of your barrel, to keep you and your rifle in top shooting form. Though it’s a common practice, it is not really sufficient to merely remove the bolt from the rifle and hold up the barrel to the light and peer through it (although, with a trained eye, one can perhaps get away with this for an initial inspection, as severe defects are obvious to the eye).

First, look at the crown and ensure there are no chips, gouges, shavings, or other damage at the edge of the crown, where it turns onto the rifling. Ensure, too, that the rifling is not rounded at the corners of the lands and grooves where they meet the crown. Next, taking a very bright light, inspect the first few millimeters of the bore at the crown, looking for discoloration or traces of copper. Look also for evidence of pitting in the bore.

PHOTO COURTESY WIKIPEDIA

From raw steel to precision instrument, barrel making is an art form.

AUTOPSY OF THE MODERN BARREL

Barrel condition, the good, the bad, the ugly—and the unbelievable! Don’t let a dirty bore turn you off, though. Always clean before looking and assessing.

The next step is to look at the throat, that part of the bore where the chamber leads onto the rifling. Look also, using a very bright light, for evidence of pitting both in the chamber and at the end of the chamber where the rifling starts. At the start of the rifling, there should be a short section that appears like a ramp leading up to each land on the rifling. This ramped section is the throat, and it should be even and consistent for each land; it should not show any signs of erosion.

Finally, and if possible with benefit of a borescope, the rifling must be inspected. First, look for misformed rifling, particularly on the corners of the lands. Second, look for areas of pitting and/or concentric rings that could indicate a possible bulge in the barrel (a fairly terminal condition, by the way). Finally, having removed the borescope, hold the barrel up to the light and try to assess the reflectivity of the bore. Is it mirror shiny, or greyed out or darkly pitted?

A last and somewhat dubious test is the use of bore gauges to measure the diameter of the bore. While this method may be okay for performing a quick assessment at a gun show, for instance, it really tells very little about the true condition of the bore.

THE BORE REVEALED

Having completed the inspection of the bore, the shooter can then take a deeper look at what problems have been discovered and decide what to do about them (if anything).

Again, let’s look at the crown first. Chips or uneven wear are generally caused by improper use of cleaning rods, particularly the segmented steel variety. Another source of damage comes through having dropped the rifle—although only the very honest will admit to that! Wear that is even in nature and that has rounded the rifling at the crown is generally associated with prolonged usage. In and of itself, this is no great problem, provided the barrel has been properly cleaned and cared for. But, if the even rounding also has minor pitting associated with it, it’s a fair indicator that the rifle has been neglected.

If copper streaks are seen just inside the crown or there is a grey or black flaky residue present, the barrel requires cleaning in order to assess its condition further. No matter the cause, a damaged crown is by no means a terminal condition. Re-crowning is a simple process and is normally conducted by a gunsmith on a lathe, though it is perfectly possible for the shooter to do at home. The process requires only a crowning hand tool. Re-crowning a barrel will remove about 3mm (¹⁄8-inch) in most cases, which is not enough to appreciably affect muzzle velocities.

Looking next at the throat and chamber, if the ramps where the projectile is led onto the rifling are not sharp and clearly defined or they are rounded off, you have uncovered a sign of throat erosion. Throat erosion may allow the projectile to potentially proceed slightly off axis to the bore, as that projectile exits the case neck and enters onto the rifling. The projectile going off axis is generally random both in direction and occurrence, and it is generally highly detrimental to accuracy. A small exception to this is when the level of throat erosion is similar to the condition of the rifling and muzzle. In this latter case, the tendency of experiencing fliers (occasional projectiles that miss the point of aim significantly), is lessened, due to the larger group size a barrel in this condition will generally shoot.

Looking at the chamber itself, there really shouldn’t be any damage here, no matter how badly the rifle has been treated, which is good, because, ultimately, there is no way to repair a chamber or throat. This does not mean the barrel should be consigned to the trash can. A worn or damaged chamber and throat can be recut, a process known as rechambering. This can be accomplished in one of two ways. In the first, the barrel is removed from the action and a fresh chamber is cut, using a cartridge-specific tool known as a chambering reamer (this tool will be crafted in the original caliber and cartridge for the particular rifle). Once the chamber is recut, the barrel is shortened at the chamber end and refitted to the action. In the second method, the barrel can be rechambered for a different cartridge, so long as it is compatible with the action and bore dimensions.

Next up for inspection is the rifling itself, preferably with a borescope. If there is discrete damage to the rifling or a dark ring is apparent (indicating a bulge in the barrel), this is generally the result of some sort of misfire or, heaven forbid, the shooting out of a jammed cleaning rod (yes, people do that). Unfortunately, this type of damage is irreparable in a barrel; in fact, it’s terminal. That said, you’ll hear anecdotal evidence to suggest that, every now and then, a bore with this type of damage shoots just fine, although such is rarely the case.

If there are areas of fine pitting in the bore, sometimes this can be remedied by bore lapping or polishing, although it should be noted that this process will not remove the pitting, just help to limit its effects on the projectile and detriment to accuracy. It should also be noted that bore lapping and polishing might help the bore and it might not. Fire lapping is a better alternative (this is identical to the running in process described later in this book).

Having searched for discrete damage in the bore and, perhaps, found none, the shooter then needs to look at the reflectivity of the bore. A bright and shiny bore can be an indicator of either a little used bore or one that has been properly cared for. A greyed bore indicates one that has seen the beginning of the formation of uniform pitting—again, not a terminal condition in its own right, but something to keep in mind as you continue to take the rifle afield. A darkly pitted bore, on the other hand, speaks for itself.

Through all this process, it would be quite easy to be too hard on the condition of a particular barrel, and a shooter could dismiss many barrels unnecessarily. It should be clearly noted that a barrel with an undamaged but worn crown, a slightly eroded throat, and a greyed-out bore will still shoot reasonably well and, in some cases, may shoot very well. In cases such as these, it is not necessarily the accuracy that may suffer directly. It is more the case that a barrel in such condition will take more fouling shots to group well, but, at the same time, will also foul faster and have its accuracy degrade faster between cleanings than a barrel in better condition.

If the shooter should feel that their barrel is on its way to being worn out, stop, give it a good cleaning, and objectively assess it. If the wear is even throughout all the components, it’s likely the bore still has life left in it.

CUSTOM BARRELS

Custom barrels are the product of specialized barrel makers. In such a barrel, the shooter can specify the caliber, twist rate, length, weight, style of taper, style of crown, number of grooves, style of grooves, number of flutes (if desired), and the barrel steel to be used. The shooter’s best friend here is the barrel maker, who, when presented with a clear definition of the barrel’s use, will be able to produce a barrel to meet those needs.

It is the responsibility of the shooter to provide a definition of the rifle’s intended use to the barrel maker. Is the barrel for a lightweight mountain stalking rifle or a Palma match rifle? Will the barrel be used in conjunction with a scope or with iron sights? What type of action will the barrel be required to mate to? These are all important questions to which the barrel maker will need answers. A good barrel maker will also ask the shooter to specify what ammunition will be used, in order to determine the correct twist rate and best length. These are the questions from which extra performance in custom barrels can be derived. That said, many shooters believe that the benefits of a custom barrel lie in the quality of the product. Although some barrel makers produce barrels of such fine tolerances that their barrels perform significantly better than one commercially produced, it is more often the case that most custom barrels derive their performance from the exacting specifications, rather than the exacting quality of the barrel itself. As with all such things, though, if the shooter is going to these lengths when choosing a barrel, they will need to pay the same amount of attention to the action and stock, as well. Performance will always be limited by the weakest link or, in our case, the most inaccurate part.

BARREL LENGTH AND WEIGHT

Barrel length and weight, when ordering a custom barrel or assessing factory options on an off-the-shelf rifle, should be driven by the shooter’s purpose for the rifle. That said, it is critically important for the shooter to have a firm understanding of the effects of different barrel lengths and weights.

Looking first at barrel length, in essence, the longer the barrel, the greater the muzzle velocity for the shooter’s ammunition. This is because the projectile is exposed to the propulsive force of the cartridge being fired for longer. Likewise, a shorter barrel will result in less velocity from the same cartridge. This general rule does have limitations. As a barrel gets longer, the velocity gains become less until, ultimately, in a very long barrel, the projectile will, in fact, begin to slow down before it reaches the end of the barrel.

The key here is choosing the right length for two factors. First, the barrel length needs to be appropriate for the caliber and cartridge. Second, the barrel length needs to be chosen so that the harmonics are correct for the projectile. The former is an easy choice. The latter is extremely complicated and goes well beyond the boundaries of this text. Without writing the necessary book on that subject, just know that, with barrel harmonics, barrel length is related to barrel weight.

Sporter Barrel Contours

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The profile of a barrel will determine its weight and taper. Although standard profiles are set, in truth, the shooter can order almost any taper imaginable. (Note: Measurements A-G here and in the charts on the following page are in inches.)

When considering what barrel length the shooter needs for a particular caliber, the shooter need only look at the amount of powder being burnt during firing. This can be broken down into several categories. Small-caliber rifles such as .223 and .22-250 need only have 16- to 22-inch barrels. Larger centerfires such as 7.62x39 and .308 are best served with barrels in the region of 20 to 24 inches, while larger calibers or magnum cartridges such as .300 Winchester Magnum and .338 Lapua Magnum are best served with barrels in excess of 26 inches. These barrel lengths will see that the bulk of the energy from the cartridge being fired will act upon the projectile to have the desired ballistic performance.

Varmint and Match Barrel Contours

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Palma Barrel Contours

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There are exceptions to these rules, and those exceptions rely purely on the purpose of the rifle. An 18-inch barrel on a .308 will make a very handy, lightweight, and convenient scout rifle with good medium range potential. A 30-inch barrel on a .300 Remington Ultra Magnum will make an excellent long-range target or stationary hunting rifle.

Hand in hand with barrel length is barrel weight. Ultimately, the barrel weight will be specified as a taper pattern, from the chamber end of the barrel tapering down to the muzzle. There are many different types of taper available, ranging from light tapers, where the outside muzzle diameter may only be .5-inch, through to heavy bench tapers, where the muzzle is 1.25 inches or greater in diameter. The only real rule here is that lighter taper barrels will warm up faster and cool down faster, factors that increase the chance that the point of aim may change. Heavier taper barrels take longer to warm and cool, thus, in a competition serial where 20 rounds may have to be fired within an allotted time period, the point of aim is less likely to change. So, the taper chosen will depend on the purpose for the rifle. If the shooter is looking for a taper suitable for backpack hunting, where the maximum range is perhaps 200 to 300 yards, a lighter taper is perfectly suitable. If the shooter is looking for a target rifle-type taper, where the rifle may be expected to fire 40 rounds with consistency, then a heavy taper is more appropriate.

The only caveat to the discussion of barrel length and taper is the question of harmonics. Without going into extensive detail, lighter barrels resonate at a higher frequency, heavier barrels at a lower frequency. The higher the frequency, the greater the opportunity for the projectile to exit the barrel while the muzzle is in motion. Again, this subject goes beyond the realms of this book, but the shooter must be aware of its presence. Likewise, it should be noted that, as a barrel is manufactured, stresses are introduced to the structure of the steel on the machined surfaces. These stress lines have the capacity to pull the barrel in a particular way, both as the barrel heats up and during firing itself. Unfortunately, the affects of these stresses are unpredictable.

Lightweight barrels are more susceptible to being affected by these factors, due to the lower ratio between surface area and total amount of steel contained within the barrel. This is the main reason lightweight barrels are bedded at the tip of the fore-end of the stock, as this type of bedding does provide support for the barrel at its midpoint and can dampen abnormal resonance. This problem can also be cured by heat-treatment of the finished barrel, most commonly by cryogenics or freezing of the barrel, to stress-relieve it (though this process is fairly hit and miss). Interestingly, it is generally unknown that the same effect can be achieved by leaving the finished barrel exposed to natural heating and cooling from the environment over a very long period, say 10 years. Like I said, that’s pretty interesting, but also fairly impractical!

TWIST RATES

Twist rates refer to the rate at which the rifling winds its way along the bore of a barrel. The twist rate is expressed as the length of barrel in which there exists one full revolution of the rifling within the bore. An example of a twist rate would be (for a .223) is 1:14, meaning there is one full rotation of the rifling in 14 inches of barrel length. Twist rate is important, because projectiles require a certain speed of rotation in order to stabilize. A projectile that has not stabilized will characteristically keyhole—the projectile will hit the target sideways. Conversely, a projectile that is over-stabilized (rotating too fast), may disintegrate before impacting the target!

The correct amount of bullet rotation and its required twist rate is dependent on the length of the projectile (longer projectiles need faster twist rates in the rifling), the speed of the projectile (faster projectiles need slower twist rates in the rifling), the diameter of the projectile, and the specific gravity of the projectile. This data and its use in the Greenhill formula can provide an adequate rule of thumb as to the required twist rate. Generally speaking, in .223 rifles, a twist rate of 1:14 is adequate to a 55-grain projectiles, while a 1:9 is required for 65-grain and heavier projectiles. In .308 rifles, 1:12 is fine for projectiles up to 168 grains, and 1:9 is required for projectiles over the 200-grain mark.

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RIFLING

Looking beyond the twist rate, the shooter can consider the style of rifling to be used. Although there are several available, which use different numbers of grooves, there are really only three styles that stand out against the plain-Jane, four- to six-groove 90-degree land-to-groove rifling.

First there is 5R rifling, which was developed for a military application. Rifling that is 5R is essentially the same as any other and can use any number of grooves. The real difference lies in the corners. The corners of 5R rifling are rounded, and this allows the rifling to grip the projectile without cutting into its jacket. This leads to less fouling, and also a better gas seal on the projectile. A further advancement of 5R rifling is that the rifling tends to be staggered, so that each land is opposite a groove. This effectively squeezes the projectile without pinching it, again, reducing fouling and enhancing the gas seal.

Lilja-styled rifling consists of using three lands and grooves. The benefits are essentially the same as with 5R, but the fewer grooves in a Lilja-rifled barrel can lead to an enhanced surface finish within the bore once hand lapped (prior to installation). Further, wear can be reduced, because there is a greater mass of steel within each land to absorb the heat and pressure stresses the rifling is exposed to when fired.

A final type of rifling is known as polygonal rifling. This style of rifling was one of the first types invented—and then essentially forgotten about. More recently, this type of rifling has been adopted by many handgun manufacturers. Polygonal rifling is generally shaped like an octagon with rounded corners, and this shape rotates through the bore to create the rifling and twist rate. Polygonal rifling, therefore, does not have distinct lands and grooves. Proponents claim this is a more accurate style of rifling, because it disturbs the projectile less than conventional riflings, which tend to cut into the projectile. While this may be the case for slow projectiles, a high-velocity projectiles might tend to slip against the rifling surfaces as it leaves the case neck, because the rifling is unable to sufficiently bite in and grip it. That said, higher velocities are achievable with polygonal rifling, due to there being less friction.

THROAT ENHANCEMENTS

The only time the shooter will ever need to specify the twist rate is when ordering a custom-made barrel, and the barrel maker will best guide the shooter as to the correct twist rate for the shooter’s purpose. Further to the twist rate, the shooter can also elect to chamber the rifle