I. Shotgun Terms

Action - the moving parts that allow you to load, fire and unload your shotgun. (See Breech, Chamber, Trigger)

Barrel selector - determines which barrel of a double barrel gun will fire first.

Blacking/bluing - the blue coloration applied to protect gun barrels.

Bore - the interior diameter of a gun barrel, which will vary according to the gun's design and intended use. The size of the bore is indicated by the term gauge.

Breech - portion of the barrel into which a cartridge is loaded.

Broken gun - is an opened rifle, hinged between the upper and lower receiver.

Butt - the rear of the shoulder end of the gun's stock.

Comb - the side of the stock that fits against your cheek.

Chamber - part of the barrel that contains the cartridge at the instant of firing.

Choke - the degree of narrowing or constriction of the bore at the muzzle end of the barrel, intended to increase the effective range of the gun. (See Full, Modified, and Improved Cylinder)

Ejector - the mechanism on shotguns by which spent shot cases are automatically ejected from the gun when it is opened after firing.

Forearm - the part of the stock that lies under the barrel.

Full choke - the tightest constriction or narrowing of the bore, producing the greatest effective range.

Grip - the narrow portion of the stock held with the trigger hand.

Gauge - the term used to describe the interior diameter of the bore. The smaller the gauge number, the larger the bore size. Modern shotguns are available in 10, 12, 16, 20 and 28 gauge. An exception is the .410 bore shotgun, which is actually a 67 gauge.

Improved cylinder - least constricted or narrowed choke causing shot pattern to widen relatively quickly.

Modified choke - moderate constriction or narrowing of the bore.

Muzzle - the end of the barrel from which the shot exits.

Over-and-under - a two-barreled shotgun with one barrel placed over the other.

Pump - a type of action that loads and ejects shells by "pumping" the forearm of the stock back and forth.

Recoil - the force with which the gun moves backwards into the shoulder when fired.

Safety - a mechanical device incorporated into a firearm design to help prevent an accidental discharge.

Semi-automatic - also called self-loading. A type of action that uses the energy from the shell that's being fired to eject the spent case, cock the action and then reload a fresh cartridge without any additional action on the part of the shooter. Semi-automatics are noted for minimal recoil.

Shot - round projectiles, usually of lead or steel. Depending on shot size and load, a shell can contain from 45 to 1,170 shot.

Shot pattern - the concentration of shot measured in a circle at a given range, usually 30 to 40 yards.

Side-by-side - a shotgun with two barrels sitting side by side. In Great Britain, the standard game shooting weapon.

Stock - the "handle" of the shotgun, the part held to the shoulder, comprising the butt, comb, grip, and forearm.

Shotshell or shell - the ammunition fired by shotguns, consisting of five components: the case, primer, powder charge, wad, and shot.

Trigger - the portion of the lock mechanism which when pulled by the shooters finger mechanism releases the sear and/or firing pin to discharge the firearm.

II. Shotgun Safety

It's Largely Common Sense
Imagine that firearms have just been invented, and you're one of the first to be introduced to the shotgun. What precautions would you take to avoid accidental injury to humans or animals, or accidental damage to objects? What, in other words, would common sense suggest?

Safe shotgun handling and shooting largely consists of good common sense applied over and over until it becomes pure instinct. And if you're a pro to whom safety rules are second nature, why not review them anyway? Like chicken soup, if it doesn't help, it couldn't hurt. And the few minutes you spend could keep you from getting careless or falling into bad habits.

Safe Handling
In simpler terms, safe handling of your shotgun is whatever prevents you from firing accidentally, or prevents injury or damage if such a discharge does occur:

• Keep the muzzle pointed in a safe direction. Never point the muzzle at any person, animal or object you don't intend to shoot. The safest directions: upward, or toward the ground (but not toward your foot).

• Keep your finger off the trigger. Fight the natural tendency to put your finger on the trigger when you hold a shotgun. If you must curl it around something, use the trigger guard. The only time your finger should touch the trigger is when you're ready to shoot.

• Keep the gun unloaded, with the action open. Make it a reflex to open the action and check the chamber whenever you pick up a shotgun. And keep the gun empty and open until you're ready to use it.

Safe Shooting
Like safe handling, safe shooting depends on common sense:

• Know your shotgun. Familiarity with your gun's basic parts and how they function is a prerequisite for safe shooting. Know how to open and close the action, for example, and how to remove ammunition.

• Don't depend on the safety. This may be the cardinal rule of safe shooting. Remember, the safety is a mechanical device and it can malfunction. The safety is not a replacement for safe handling and shooting practices.

• Make sure gun and ammunition match. If there is any question about compatibility between shot shell and gun, don't fire! The gauge of the shell must match the gauge of the shotgun. The gauge of the gun is likely to be stamped on the barrel. The gauge of the shell will be indicated on the box, and on each shell.

• Don't carry shells of mixed gauge. Whenever you're through shooting, immediately remove unfired shells from your clothing. It's a good way to avoid mixing ammunition. The drawings that follow illustrate the explosive--and potentially disastrous--effect of placing both a 20 and a 12 gauge shell in the same gun. Remember your fingers would have been placed directly over the blown out portion of the forearm!

• Never put a three inch shotshell into a gun that's chambered only for standard 2¾ inch loads, because the crimp at the mouth of the cartridge won't have room to open fully, and dangerously high pressures will result.

• Be sure before you shoot. If you're not absolutely certain that you've identified your target, don't shoot! And be equally aware of what's beyond your target. If it's another person, or an object that shouldn't be hit--no matter how far--don't shoot!

• Protect your eyes and ears. Guns make noise. Noise affects your hearing. Guns also emit debris and gasses that can injure your eyes. Ear protectors and safety glasses are a must.

• If your senses are impaired, don't go shooting! Among the world's worst combinations are firearms and alcohol, and firearms and drugs.

• Don't run the risk of a clogged barrel. Barrel obstructions can cause gun bursts. If you've stumbled and jabbed the barrel into the ground or crawled to surprise your quarry, unload and check the barrel for mud or snow.

• Don't rest your gun on your feet to keep it out of mud or snow.

Eye & Ear Protection
Just for a moment, think of how much your vision and hearing mean to you. Then consider the effect on your life if either of these senses was impaired. How many activities that you take for granted would you have to curtail? How many daily pleasures would you have to forsake? As a shot gunner, you owe it to yourself to protect your eyes on every shooting occasion.

Field Etiquette
Etiquette is just good manners. In shooting, etiquette also introduces another element of safety. Practice shooting etiquette in the field and you'll be a safe--and popular--shooting companion.

• Never shoot across another shooter.

• Don't interfere with another hunter's dog. Period!

• Never put your gun off safety until game has flushed.

• Don't shoot if a dog is directly behind low flying birds.

• Make sure every member of your party is wearing an article of blaze orange clothing.

• Agree prior to going into field what are the safe zones of fire.

• Always maintain a "straight line" when hunting with a partner and/or guide.

• If you don't know where your partner and guide are, don't shoot!

III. Swing & Lead

Many shot gunners have wondered how much displacement of the pattern is caused by the motion of the barrel as the shot is fired. Everyone has noticed, when throwing an object from a moving car, that its path has both an outward component from the force of the throw and a forward component from the motion of the car.

This same effect applies to shot patterns. If, for example, a shooter fired on a target crossing 30 yards distant with a load producing a muzzle velocity of 1300 f.p.s., and swung the barrel at 10 m.p.h., the initial direction of the shot charge would be altered by about 26 minutes of angle, or about 8" at 30 yards.

It readily can be seen that this effect adds only a little to the forward allowance necessary to hit the target. In shot gunning, there is no substitute for lead.

IV. Base & Brass

The near-universal use of plastic shotshells has rendered obsolete the old terms high and low base, but plastic shells are made in a wide variety of head designs, and even without brass heads.

During the paper-shell era, solid paper wads (in the shell base) were made in high, medium and low configurations, depending on the powder being used. A high base wad was called for when small powder volumes were used.

The brass height was inversely related to base height. If the top of the brass was at the same level as the top of the base wad, tubes would often separate at the head when the cartridge was fired. So low-base shells -- those with a large, heavy powder charge -- used high brass so the brass would be above the top of the base wad.

Conversely, in a field or target load where a high base wad was used with a light powder charge, low brass was used so the top of the brass would be below the highest point of the base wad.

Today the brass portion of the shell (more often brass-colored steel) has a primarily decorative role. All-plastic shells like Cavim, Eclipse and Activ have demonstrated that some compression-formed plastics are quite strong enough for shotshell use with no metal reinforcement (it should be noted that all-paper shells were tried, too). Tall brass is still used on high-powered shells (especially those from Italy), but its purpose is marketing appeal.

V. Shot Spread

Shooters often want a rule of thumb to estimate shot spread at a given range. So many variables are involved -- choke, velocity, shot hardness, etc., that a firm rule is almost impossible to devise.

A good rough rule, however, is this one. When fired from a full-choke gun, the pattern will spread roughly 1" per yard. When fired from an improved-cylinder gun, it will spread roughly 1 ¾" per yard. Other degrees of choke will spread proportionally.

It should be noted that this applies to any gauge, since extreme spread is little affected by gauge. The larger gauges simply have the ability to fill in the pattern with more shot. Bear in mind that choke, or constriction, only governs the spread of shot; it has no effect on the energy of the individual pellets, and a full choke is no excuse for attempting kills at ridiculous ranges.

VI. Shot Size

Table 2.1 Shot size

VII. Magnum Shotshell Advantage

 Many shot gunners buy 2¾" or 3" magnum ammunition under the impression that striking energy of each pellet is somehow greater. This is not the case. The advantage of magnum shells is the greater shot charge weight, and thus pattern density, they provide.

Magnum shells are generally no greater in velocity than high-velocity shells, so each pellet is driven at a similar speed. The magnum's advantage is that more pellets are thrown.

It is this increased pattern density that allows magnum ammunition to provide better performance at long range.

The figure shows how the pattern diameter corresponds roughly to the range. It should be remembered, however, that it is the area that the shot charge must cover that is important. Areas of circles are to each other as the squares of the diameters. Even a small increase in diameter results in a large increase in area, and a correspondingly severe thinning of the pattern.

For equal pattern density, the range of the 1½ oz. Load is to the range of the 1¼ oz. Load as the square root of 1.5 is to the square root of 1.25 or about 1.10. Thus the range increase for the heavier load is about 10%.

Of course, when magnum and standard ammunition are compared at the same range, the magnum provides "insurance" pattern coverage, though at a cost in expense, muzzle blast and recoil. 

IIX. Ammunition & Choke Suggestions

Table 2.2 Ammunition & Choke Suggestions

IX. Shot Penetration

It has been thought by some hunters that small shot penetrates better because its small cross-section will encounter less resistance.

This idea is quite incorrect. The fallacy in it is obvious when it is carried to its logical conclusion; that a round cannonball would penetrate a much shorter distance than a small shot pellet.

The belief would be correctly founded if penetration by shot pellets took place as the result of an outside force applied to the pellets during penetration, pushing them through the target. This situation does not exist.

The only force carrying a projectile through its target arises from its own velocity and weight. Assuming like velocities, then the only factors making for different penetrations by non-deforming round shot will be weight and area. The weights of spheres of the same material will be to each other as the cubes of their diameters. However, the areas they present will be only as the squares of their diameters.

With the available force varying as the diameter cubed, and the resistance varying only as the diameter squared, it is obvious that the penetration will, be as D3 divided by D2, which equals D itself. That is, penetration goes up strictly in accordance with the diameter of the shot.

This amply confirmed fact applies to penetration both in solid substances and in air, and is the reason why large shot retain their velocity in flight better than small shot.

X. Drop of Shot Charge

Trajectory of rifle and pistol bullets is extensively studied and is the subject of countless tables for finding drop at various ranges. Each pellet in a charge of shot drops as it flies toward its target due to the force of gravity, just as a single rifle bullet drops in its flight.

The amount of drop, however, is too small to require consideration in most real-world applications. For example, the drop of a shot charge at 50 yards, about the maximum range for most shot gunning, is about 5". Leads on flying targets at that range are a matter of yards, so the 5" drop fades into insignificance.

During market-hunting days, when professional wildfowlers used 8ga, 4ga, and even larger punt guns to flock-shoot waterfowl at long ranges; drop was a more important consideration. But since most shooters have enough trouble just calculating lead, they will do better to disregard drop.

XI. Shotgun Gauges

The system of expressing shotgun bore sizes by gauge rather than by decimal or metric measurements is, like many things, relating to smoothbores, a result of long tradition. Numbered gauges represent the number of round lead balls fitting the bore required to make a pound. Letter gauges were used for some of the very large bore sizes.

There was originally no distinction in this connection between shotguns and ball guns, since all were smooth-bored and could be fired with either shot or ball. The gauge system was continued for rifles in gauges up to No. 1 (1.669") until recent decades, and is still correct for smoothbores intended to shoot a single bullet. Its eventual abandonment for rifles was due to the great elongation of many rifle bullets, which caused bore size to be no longer a useful indication of the weight of bullet thrown.

The use of this system was due in part to the inability of the early gun makers and other craftsmen to perform accurate measurements. Not until the introduction of precise tool making and gauging techniques by Sir Joseph Whitworth, beginning about 1840, was it possible to measure gun bores, for example, with anything like the accuracy which we now consider commonplace. By contrast, it was always practicable to classify bores by approximate weight of the ball they took. This did not then signify a precise specification of bore diameter. The present standard bore diameters, though specified on the old rule, became possible only with the ability to make accurate measurements.

Table 2.3 English small arms gauges as given in the Gun Barrel Proof Act of 1868

Note that the gauge system goes down only to No. 50, which was until comparatively recent times considered a small bore. Below that the actual bore diameter is used. So far as required, these gauge sizes are also used in the United States.

A more fundamental consideration in favor of the gauge system, however, was the fact that it rated the gun on the charge it shot. This was and is more important to the user than the mere size of the hole through the barrel. Even today, when extreme efforts are made to get disproportionately large charges into shotshells rather than go to a slightly larger gauge, the gauge system retains a great deal of usefulness in this way.

The gauge system has won out not only in the English-speaking countries but all over the world. This remarkable success is probably the best measure of its merit.

XII. Shotshell Lengths

Shotshells once were made, both here and abroad, in an incredible profusion of varieties, with thousands of combinations of shell length, powder, wads and shot sizes available.

Today, the world has generally agreed on the U.S. 2 3/4", 3" and 3 1/2" dimensions for shotshells, but there are exceptions, especially in European target and light field loads.

These are found in lengths as short as 2" in Britain and on the Continent, but importers rarely bring in anything shorter than 65 mm (2 9/16"). Other common sizes are 67 mm (2 5/8") and 67.5 mm (2 21/32"). The standard 2 ¾" shell measures 70 mm, while the 3" Mag is designated 76 mm (dimensions approximate fired length).

XIII. Shotgun Patterning

Shotgun pattering can be as simple as firing against a painted steel plate or as complicated as using the 100-field German Halensee target. NRA has for many years used an eight-field target that provides a good deal of information without making pattering an unbearable task.

To pattern by the NRA method, set up a piece of Kraft paper at least 48" square on a framework that allows the shot to pass through freely. A sturdy barbed-wire fence will do in a pinch. Draw an aiming point large enough to be seen from the standard pattering distance of 40 yards (25 yards for .410s or skeet guns). A spray can of flat black paint makes an aiming point in one quick squirt. Mark the top of the target.

Step off the proper distance and fire, preferably from offhand and without taking deliberate aim.

For "Dope Bag" evaluations, the NRA Technical Staff fires 10 patterns from each barrel or choke tube under evaluation. This provides a very high margin of confidence when results are totaled and averaged. Most shot gunners will want to avoid the labor of shooting and counting so may patterns, but at least three or four should be fired to minimize the influence of flinching or other factors.

To evaluate the pattern, draw a 30" circle that encloses the greatest possible number of pellets. It may be necessary to draw the circle slightly off the pattern sheet. Next, draw a 21.21" circle concentric with the larger one. Then quarter the two circles with a straightedge. This divides the circle into eight equal areas.

Count each area and mark the total. Then add the totals for the inside four sections and the outer four. The total number of hits in the 30" circle is totaled next. Select five shot shells from the lot being tested and count the number of pellets in each. Then average the five totals. Divide the average by the number of hits in the 30" circle for the barrel's pattern percentage. The operation can be repeated for the 21.21" circle and the 30" ring formed by the four outer sections.

The gun's impact point is located by measuring the distance from the intersection of the quartering lines from the center of the aiming point. A properly regulated shotgun will place its pattern evenly around the aiming point (trap guns are generally designed to shoot high). Consistent pattering away from the aiming point, especially left or right, should be corrected by bending the barrel or by installation of an eccentric choke tube.

Pattern testing is one of the most tedious tasks in the firearms world. But it is the only method that allows accurate conclusions to be drawn about shotgun performance.

XIV. Shot/Pellet Counts

Table 2.4 Nominal Pellet Counts for Lead Waterfowl And Buckshot Loads

Table 2.5 Metric and U.S. Shot Conversions

Table 2.6 Nominal Pellet Counts for Lead Field Loads 

Table 2.7 Nominal Pellet Counts for Steel Shot

XV. Buckshot Vs. Slug

Certain states and localities prohibit rifles and require the use of shotgun slugs or buckshot for big game hunting, usually because they are considered safer for use in congested areas. Both slugs and buckshot have a very limited range in comparison with rifles.

Were it not for such laws, it is doubtful that many hunters would select slugs or especially buckshot for big game hunting. Range and accuracy are decisively inferior even to low-powered rifle cartridges, and some big-bore pistol rounds provide better energy.

Shotgun slugs should not be used at ranges greater than about 75 yards. Maximum effective range is limited as much by the slug's rapid decay of energy and velocity as by its poor accuracy. A typical shotgun slug loses 40% of its striking energy in traveling the first 50 yards. It loses 55% of that muzzle energy in traveling 75 yards, 60% in 100 yards. The substantial muzzle energy (2365 ft.-lbs. for a typical 12-ga. 1-oz. Slug at 1560 f.p.s.) drops to 1345 ft.-lbs. at 50 yards, and less than 1000 ft.-lbs. at 100 yards.

Accuracy of shotgun slugs is adequate for deer hunting at ranges up to about 50 yards from almost any shotgun, but the performance to be expected can be determined only by shooting a particular gun. Barrels vary considerably, and the type and brand of ammunition can have a considerable influence in the gun's grouping potential.

The dispersion of shotgun slugs is not inherently linear with the range. The typical dispersion of slugs at 100 yards is about 2.3 times what the same barrel and ammunition will do at 50 yards.

Shotgun slugs are made of very soft lead so they will expand to fit the bore on firing. Measurements based on spark shadowgraphs of slugs in flight indicate the axial length of a typical slug is reduced by about 30% during the few milliseconds from the strike of the firing pin until the soft lead projectile is ejected from the muzzle.

Buckshot is even more a short-range proposition than the slug. It is unreliable at ranges greater than about 25 yards, especially in the densely-wooded areas where it is most often required.

Though buckshot loads have been considerably improved in recent years by the use of harder shot, plastic wads and buffers, the improvements have been more in reliable lethality than in added range.

It has been a generally-accepted rule of thumb that 600 ft.-lbs. is the minimum energy required for reliable taking of whitetail deer. At 20 yards, this would require hits by three (of eight from a 2 ¾" shell) pellets of No. 000 Buck, or 12 (of 27) pellets of No. 4 Buck. No. 4 and No. 1 Buck are primarily used for very short-range hunting and some law-enforcement uses; the traditional 00 or 000 Buck loadings are best for deer. While No. 4 Buck has a per-pellet striking energy about equal to the .32 ACP pistol round, the energy of 000 Buck more closely resembles the usual 158-gr. .38 Spl. round.

As is the case with slugs, hunters should carefully pattern several types and brands of buckshot ammunition to find the proper load for a particular gun. A load that will place all its pellets in a 19" circle at 25 yards is acceptable for most deer hunting.

Above all, keep shots within 25 yards - anything else constitutes unethical hunting.

XVI. European Choke Codes

In this country, choke designations are simply spelled out or abbreviated in some understandable way. In Europe, chokes are designated by codes. These are generally placed on the barrels or monobloc of double guns and on some visible part of choke tubes. While there are some variations among manufacturers, the general rule is: The more marks, the more open the choke. Marks are most often asterisks or stars on the gun itself, while choke tubes may be marked with a simple file cut.

The most common system is:

It should be borne in mind that many European guns have been made for fiber-wadded shells, and both bores and chokes are tight by American standards. Pattern-testing is essential to determine true pattern performance, especially when using U.S. ammunition in European guns.

XVII. Bore & Choke Dimensions

Shotgun bore sizes and choke constrictions have changed over the years and still vary widely among manufacturers and especially among nations. European guns often have rather tight bores, while some target shotguns have large bores and very gradual forcing cones to promote tight patterning. The increasing use of steel shot likely will have an effect on choke dimensions, since steel shot requires much less constriction for tight patterns.

Table 2.8 Gauge and choke constriction

Information provided by NRA FIREARMS FACT BOOK and BLACK'S WING & CLAY.