Marksmanship

Marksmanship refers to the art or skill of using a firearm, such as a rifle or a pistol.

Fundamentals overview
The basic fundamentals of marksmanship can be described in a number of ways.

Possibly the most succinct version of the principles of marksmanship is that used by the British and Australian Army:


 * 1) The position and hold must be firm enough to support the weapon.
 * 2) The weapon  must point naturally at the target without undue physical effort.
 * 3) Sight alignment and sight picture must be correct.
 * 4) The shot must be released and followed through without any undue physical disturbance to the position.

The US Army similarly breaks marksmanship principles into four fundamentals, however states them more verbosely:


 * Steady position - Regardless of stance or position, the weapon must be held the same way for each shot and in a manner that will facilitate the least wobble (natural movement of the body as indicated by the sights.) The basic method of firing taught to novice-level shooters and soldiers is the prone supported position; that is, on your stomach with the position supported by another object, usually a sandbag.
 * Aiming - Sight Alignment (the relationship of the front and rear sight or clear, centered reticle in an optical sight) is most important to accuracy as it helps eliminate angular error. The aligned sights placed on target is Sight Picture.  The front sight or reticle should always be positioned in the same spot. These two factors ensures that shots fired, if the other fundamentals are correctly applied, will hit in the same general area. Normally a center hold (center mass of the target) is preferred but other hold points may be used.
 * Breathing Control - [Not everyone agrees that this is] The least important factor. Normally, the firer should press the trigger during the natural pause after exhalation. The breathing sequence should be as follows: inhale, exhale, hold, squeeze.
 * Trigger Control - The trigger is the interface between shooter and "machine", and therefore requires careful attention. The shooter must smoothly squeeze the trigger straight back with increasing pressure without attempting to anticipate when the round will fire.  Once the grip/hold is achieved, only the index finger of the shooting hand moves during the trigger squeeze.  During initial training a marksman should strive for a "surprise break."  There is no "wrong" way to place the index finger on the trigger provided that the shooter is able to consistently move the trigger straight rearward.  Begin with the pad of the trigger finger and adjust positioning as needed.
 * The rifle must never be pointed at a c/o or fellow soldier. It must always point down range or at the enemy.

Stance or position overview
The weapon should point toward the target, without effort or strain. The ideal position is attained by "natural point of aim" in which no undue muscular tension is required to keep the sights on target.

In order to ascertain the natural point of aim (POA) and to adjust the natural POA to the desired POA the shooter undertakes a procedure called "test and adjust".

The test portion consists of the shooter closing their eyes and relaxing the grip on their weapon while still holding it in the firing position. The shooter then re-firms his grip and opens his eyes. Where the sights are now pointing is the natural POA.

To adjust the natural point of aim when shooting from the standing or squatting position, the shooter alters his/her position by moving his/her feet. With other positions, the shooter moves their body. For example, in the sitting position the shooter would move their backside. In the kneeling position the rear leg/foot is moved. Moving back foot (standing) or body (prone) forward generally lowers the point of aim. Moving it rearward raises the point of aim. Similarly, moving the rear foot or body to the right moves the point of aim left and vice versa. The shooter continues to test and adjust until the natural POA coincides with the target.

Fundamentals of Rifle Marksmanship

 * Breathing Control : Oxygen deficit leads to an unsteady hold as the muscles require more oxygenated blood. Therefore, the trigger should be pressed at a point in the respiration cycle (inhale, hold, exhale) when the shooter is steadiest.  Various techniques work for different individuals: usually after exhaling half a breath or exhaling the entire breath.  Since it is almost impossible to measure half a breath with consistency, the latter technique is most popular.

The rifle should never directly be rested on a hard surface such as a vehicle roof, window frame, rock or sandbag wall. Instead the support hand should rest on the hard surface and the rifle should rest on the support hand. The reason for this is that laying the rifle directly on a support will introduce changes to the vibration pattern of the rifle when firing. Placing the hand between the rifle and the support surface, reduces (but does not eliminate) the changes to the vibration patterns of the weapon.
 * Support : The rifle is held at two points: with the firing hand and with the support hand. The firing hand not only grasps the portion of the stock around the trigger group, but exerts steady rearward pressure into the “pocket” of the shoulder.  The support elbow is held directly under the rifle, without a hard grip by the hand which may introduce lateral “wobble”.


 * Cheek Weld : Consistency in sighting begins with proper “cheek weld”, positioning the cheek at the same place along the stock. Besides before and after placement of the “weld”, it also determines the height of the eyes in relation to the sights or scope.


 * Natural Point of Aim : Every marksman has a natural point of aim (NPOA), the optimum position of the body in any shooting stance. For instance, in prone, the shooter aligns himself with the target in such a manner that his sights rest comfortably on the bull’s eye without excessive muscular tension to maintain a desired sight picture.  The position may be “fine tuned” by subtle movement of the arms, elbows, or feet.  NPOA can easily be checked by finding a comfortable position with sights properly aligned, then closing both eyes.  Inhale and exhale.  When the eyes are opened, the sight picture should remain unchanged.  If not, adjust as necessary.


 * Sight Alignment
 * With metallic sights, proper alignment with "U" notch sights places the front sight post squarely within the “notch” of the rear (square) sight. The top of the front sight should remain even with the top of the rear sight, with equal “daylight” on either side of the front site within the notch. If the rear sight is a peep sight ( circular aperture) or “ghost ring”, the tip of the front sight should be centered in relation to the circle. When shooting at longer distances, the rear sight will be elevated to compensate for the bullet’s ballistic “drop”, but the sight picture should always remain the same.  Make everything consistent.
 * With optical sights, such as telescopes, proper alignment is obtained when there is no dark portion or “shadow” at any point in the circumference of the field of view. This will ensure that you are always sighting through the center of the scope. Scope parallax adjustment must put the sight cross hairs and target image in the same focal plane to avoid a shift in relative position with small movements of the eye.


 * Sight Picture : Sight picture is the placement of the sights (properly aligned) in relation to the target. In most formal competition, the desired sight picture is the front post tangent to the bottom of the bull’s eye, yielding a “six o’clock hold”.  The six o’clock is almost universally preferred to placing the front sight at the intended point of impact in the center of the target because the resultant picture is inevitably inconsistent. At the time the shooter fires the shot, the tip of the foresight should be in clear focus. This will render the rest of the sight picture blurry. This ensures correct sight alignment.
 * Trigger Control : Trigger control is commonly considered the easiest aspect of marksmanship to explain and the most difficult to accomplish. A perfect release or “break” results from steadily 'squeezing' the trigger straight back (usually with the pad of the trigger finger, not at the first joint, although the firing of a revolver in double action may typically be described as using the first joint) with no lateral pressure.  It should occur at an instant when the shooter does not expect the rifle to discharge, resulting in a “surprise break” that is immune to anticipation or “flinch” that disturbs the sight picture. More in depth, the ability to control trigger "creep", as in the dead space before the trigger works the action; overtravel, the distance the trigger travels rearward after it causes the action to fire the gun; reset, the minimal forward movement of the trigger to be made ready to fire again.


 * Follow Through : Follow through is important in developing consistency. While the bullet leaves the rifle’s barrel within milli-seconds of ignition, the shooter benefits from “staying on the target ” in order to determine where the round likely struck.  With experience, shooters can tell with extreme precision whether the projectile has struck the target or elsewhere.

Pistol Marksmanship

Line of Sight: Some shooters consider aiming with a pistol more challenging than with a rifle due to the smaller sight radius - the distance between the rear and fore sights. The key is, as with shooting rifles, is to line up the front notch at the front of the pistol's slide within the two rear notches at the back of the pistol's slide. Do this, and almost every time your shot will hit its mark.

Control: Many shooters have problems with controlling the recoil of a pistol. This problem is not as often shared by rifle shooters due to the energy of the recoil of their rifles dissipating against their shoulders. However, when shooting a pistol it is far more difficult to control the weapon when it is just held by your hands as it often recoils up and back at the same time.

Posture/Stance: When firing a sidearm it is important, as with firing any weapon, to maintain a proper firing stance at all times. There are several wrong shooting stances that many shooters use obliviously. One common one is that of a shooter holding the pistol and slightly leaning away from the pistol as if afraid it will spring back and hit them in the face. This will not happen unless you let the pistol fly out of your grasp, or place your self directly behind it. A correct shooting stance includes a firm two handed grip, strong hand extending out towards target with the "weak" or support hand slightly pulling rearward as to "lock" in a stable platform for the pistol, knees bent and feet approximately shoulder width apart, upper body slightly leaning forward into firearm. By leaning forward, with the firearm held in such a manner the arms are stable and take up recoil better than not having a fully extended arm, the upper body also dissipates recoil much better, in conjunction with slightly bent knees and proper foot placement creating a very suitable firing platform for the pistol. Resulting in an improvement in accuracy, and with better recoil management, the ability to put faster follow up shots on target

Rifle shooting positions
There are four basic positions for shooting rifles or carbines.


 * Standing or offhand: Erect on both feet with the rifle supported by the strong hand and the support hand. This is the fastest position to assume but is the least steady.


 * Kneeling: Generally with one knee on the ground and the support elbow resting atop (improperly) or (preferably) slightly forward of the elevated knee. Steadier than offhand and faster than sitting or prone.


 * Sitting: Two variants include "open legged" or "cross legged" (ankles apart or overlapping) with both elbows supported on the knees or thighs. The best all-round supported position, as it permits a fast, steady platform suitable to rough terrain.


 * Prone: Lying on one's stomach with the support hand beneath the rifle. Feet may be splayed or closer together but most shooters find it helpful to bring the strong-side knee forward. The steadiest position, but requires more time to assume than any other and may be unsuitable for some terrain or where ground cover obscures the target.

Other nonstandard positions include the squat ("rice paddy prone"), "speed kneeling" with both knees on the ground, and "supine", where the firer lies on his/her side, with the rifle lying on the bent lower leg; the sight is usually mounted on the end of the stock and as such the rifle is designed to be shot in this position only.

Grip or hold
The grip or hold depends on the shooting discipline (i.e. what is allowed under the rules of competition) and what is practical. For instance, in the IPSC pistol discipline, the most used grip is two handed, although some stages will be designed such that the shot must be taken with either the weak or the strong hand only.

When gripping a handgun, "shake hands" with the grip. Take a firm and high grip, wrapping the three lower fingers around the grip with the trigger finger resting along the slide away from the trigger and trigger guard.

When using iron sights, the firer must focus on the tip of the foresight at the moment they release the shot. The rear sight and the target itself will not be in focus. This assists in assuring correct sight alignment.

Accuracy & Precision
Two methods of looking at the success of a shot group involve accuracy and precision, where accuracy is defined as 'the ability of a measurement to match the actual value of the quantity being measured,' and precision is defined as 'the ability of a measurement to be consistently reproduced' (www.dictionary.com).

Precision
Precision also referred to as "intrinsic accuracy", is measured by the group, where hitting close to bulls eye does not affect precision rather than the fact that all bullets in the group landed very close to one another. Hence, the smaller or "tighter" the group, the better the Precision.

Major factors that affect precision are:
 * shooting position
 * the rifle
 * the shooter
 * the weather (within the span of the group)
 * ammunition (especially in competitions, and surgical sniping. However, ALL firearms have particular likes and dislikes, causing malfunctions for even the highest quality ammunition. It's up to the firearm owner to test for what his or her firearm can reliably feed and function with while using)
 * elevation
 * humidity
 * Coriolis effect
 * breathing pattern
 * parallax (scoped rifle)
 * execution of proper marksmanship fundamentals

The intrinsic accuracy (precision) of each of these components can be measured separately. The typical unit of measurement for rifles and scopes is MOA (Minute of Angle). There are 360 degrees in a full circle and 60 minutes per degree.

"Mechanical Accuracy" refers to the accuracy of the rifle and the ammunition. The accuracy of a given weapon will actually be equal to the square root of the sum of the squares of the dispersion caused by each individual factor, such as weapon, ammunition, shooter skill, weather, etc. For example, if a rifle is capable of performing at 0.5 MOA, but the ammunition you are using is only capable of 1.1 MOA, the accuracy of the weapon and ammunition combination will be the square root of 0.5^2 + 1.1^2, or approximately 1.2 MOA. However, if the shooter is only capable of 4 MOA, then using this ammunition and rifle, the average MOA will be [0.5^2 + 1.1^2 +4^2]^0.5 = @4.2 MOA, in perfect weather.

We have the least control over the weather and other environmental factors. We have the most control over the accuracy of the individual shooter. Do not be overly concerned about upgrading your rifle or ammunition (to a lower MOA) until your own MOA approaches a similar degree of accuracy.

The intrinsic accuracy of all these components is measured by the tightness of the group as discussed below.

Accuracy
The ability to hit the target (as opposed to shooting a small group) is probably the more commonly perceived measure of accuracy amongst new or non shooters. This technique can be referred to as practical accuracy, because, generally speaking in field shooting, hitting the target is the point of the practice of shooting. This accuracy is a measure of the shooter's ability to cause the group to hit the target, by adjusting the point of aim. The operation or exercise of causing the group to fall on the target, by adjusting the point of aim, is called "application of fire". As with any weapon when firing and aiming for your target you must know that the bullet gradually moves downward when fired so when aiming at a target it is best to aim a little above it to get an accurate shot at your target.

Precision Leads to Accuracy
Without precision, or repeatability of the above-mentioned components of precision, a high degree of accuracy is nearly impossible. In order to accurately strike a target, the shooter must adjust the aim to account for several variables, and to the extent the repeatability of the firearm or conditions is poor, this adjustment becomes correspondingly uncertain --- in other words, with poor precision the shooter simply will have to guess. For example, suppose a given cartridge produces a wide and unpredictable variation in muzzle velocity, and that all other elements of the firearm are highly precise. In this case, the shooter has very little idea of where the shot will go, as the amount of drop for which to compensate is highly uncertain, and the shooter will simply have to hope for the best.

Maximum effective range vs. accuracy
Firearms are considered ineffective beyond the distance a carefully fired shot is guaranteed to strike the target. At longer ranges, a miss could occur that might endanger the marksman's mission. In those instances, other weapons may be preferred over marksmen/snipers equipped with special sniper rifles, even though the situation may be an otherwise ideal job for a sniper.

For example, in counter-sniper roles a sniper might spot a target that is out of range for a sniper rifle, and so the sniper may need to call upon a machine gunner to attack it. A machine gun using the same ammunition as the sniper rifle can be effective at a much greater range due to lower accuracy requirements for effective use.

Here is a simplified example to illustrate why, counter-intuitively, a less accurate weapon of the same calibre may actually have a greater effective range than a sniper rifle: For human targets in military sniping, snipers aim at a "target circle". The equations that describe the approximate relationships between range, accuracy, and the target circle, as used in this section, are as follows:
 * (Target circle (inches) / Accuracy (MOA - Minute Of Angle) * 100 = Range meters
 * (Range meters * Accuracy (MOA) / 100) = Target circle inches

Also note that "target circle" is used exclusively even when "cone of fire" or "group size" may technically be more accurate. These terms have subtle differences that are not important for the purpose of this section, and they are left out to avoid introducing unnecessary complexity in illustrations and examples that have been intentionally simplified.

The target circle is typically about 8 inches in diameter, corresponding to an imaginary circle on the vital area of a person's chest. For a common sniper rifle capable of 1 MOA accuracy, the maximum effective range (the range at which the bullet impact point is guaranteed to be within an 8-inch circle on the first shot) is about 800 meters.

In contrast, a machine gun using the same ammunition with a low accuracy of only 6 MOA will typically have a greater maximum effective range of about 1,100 meters. At that range and accuracy, a machine gun has a larger target circle of about 66 inches. The machine gun's target circle is much larger due to its rapid fire capability, which allows a machine gun to strike with one or more hits and numerous misses at random locations within the target circle.

While a machine gun's large target circle means that its effective range can be longer than a sniper rifle's, note that the design of a weapon is more likely to determine its effective range than the maximum range of its ammunition. The maximum range of common 7.62 × 51 mm NATO ammunition is a comparatively large 3,725 meters, and both machine guns and sniper rifles are not able to use even half of the maximum range of the ammunition effectively, largely due to unpredictable atmospheric disturbance of the bullet's flight path. The maximum range is much larger than the maximum effective range. The corresponding disadvantage is that the machine gun may need to fire dozens, and perhaps hundreds of rounds before scoring a hit.

What is a Group?
A group is defined as a series of shots fired at the same POA, or point of aim, from the same position and hold. Generally speaking three shots is the minimum considered necessary to form a group and groups of three, five, ten or more are commonly used for measuring accuracy for testing and comparative purposes. Generally speaking the more shots fired in a group, the more useful the data is for comparative purposes.

Certain shooting disciplines, styles, shooter accuracy, or experience may define the number of shots required for a group in their competitions or practice (as in teaching trigger control). It may also benefit newer shooters to use a higher round count group, to increase their probability at placing multiple rounds together(encuraging confidence), and highlighting the ones that have "pulled", to reinforce what has been learned earlier in the fundamentals.

How is a group measured
The group is a measure of the angular dispersion of a series of rounds. There are two methods commonly used to describe a group:


 * The first and perhaps easier to understand for the lay person is the absolute size of the group and the range. E.g. "4 inch group at 100 yards".


 * The second and more succinct method is to simply state the angular dispersion of the rounds in the group as an angle. The usual units for this are "minutes of angle" (MOA). A minute of angle is 1/60th of a degree of angle.

It is important to remember that both methods describe the same thing, i.e. the angular dispersion of the shots. Generally speaking MOA is the preferred way to describe a group as it is a single range neutral number.

For most purposes shooters approximate 1 MOA to be a group of 1 inch at 100 yards which is accurate enough for all but the most precise measurements.

Note however that the size of a group may vary at different ranges, e.g. a rifle may fire 4 MOA at 100 m but fire 2 MOA at 600 m. Reasons for this might include different stability at different ranges in the trajectory. However despite this when comparing accuracy it is usual to discuss the size of the group at a given range, often 100 m. Also despite the fact that, in reality, the accuracy of a rifle may vary at different ranges, it is common to interpolate the accuracy of a rifle at one range from the known accuracy at another range. I.e. it is commonly assumed that a rifle that shoots 1 MOA when measured at 100 yards, i.e. a 1 inch group at 100 yards, will still shoot 1 MOA at 200 yards, i.e. a 2 inch group at 200 yards.

How is a group useful?
As indicated above, the group is the measure of the intrinsic accuracy of a rifle, ammunition, shooter or some other component in the shooting combination in a given set of conditions. By this we mean the accuracy potential of the combination when ignoring, removing or otherwise canceling, as far as possible (perhaps by conducting all testing in the same environment at the same time), external factors, such as weather.

What exactly does the group measure?
The size of the group is in fact a measure of the consistency of rifle, ammunition and shooter. The smaller the group, the more potentially accurate the variable or variables being measured. This is because the smaller the group is the greater the chance of a round striking the same place as previous shots fired in the group. Here's the way to measure a group accurately: You need a caliper (digital-readout calipers are much easier to use than dial-readout models) and the ability to subtract. First, measure the outside spread of the two widest shots in the group. Then, subtract from that figure the diameter of the bullet you're shooting. Let's say you take your .270 and shoot a group that measures 1.313 inches. Subtract from it .277, which is the actual diameter of the bullet, and you get 1.036 inches, which is your group size.

What does a group NOT measure?
A group does not measure the ability of a rifle/marksman/ammunition or any other single component or combination of components to actually hit a target.

Theory of Small Arms Fire
The accuracy of small arms fire is affected by several factors. These include:
 * The inherent mechanical accuracy of the rifle,
 * The inherent mechanical accuracy of the ammunition
 * The firer's ability
 * Weather conditions

Mechanical Accuracy of Weapon
The mechanical accuracy of the rifle is affected by several factors including:
 * The quality of manufacture, eg the closeness and consistency of the construction.
 * The design of the rifle, including the stiffness of the barrel, the action, the amount of play if any between components, the barrel mounting, eg free floating, dampened, locking mechanism
 * The materials that the rifle is constructed of, especially their environmental stability (i.e. their stability in the face of changing environmental parameters, such as temperature, humidity and the like).

Mechanical Accuracy of Ammunition
The mechanical accuracy of the ammunition is dependent on several factors including:
 * The quality of the propellant and accuracy of quantity of propellant
 * The quality of the projectile (diameter, mass, and concentricity)
 * The quality of the case

The firer's ability

 * The firer's knowledge - affects the firer's ability to apply the principles of marksmanship to the practice of marksmanship.
 * The firer's strength - affects the firer's ability to hold the rifle correctly and with minimal effort, which reduces shake/tremor.
 * The firer's fitness - the fitness of the firer affects the firer's ability to breathe, and control the breath and shaking/tremor due to breathing and oxygen levels in the blood and muscles.

Weather
There are several environmental (weather) factors that affect accuracy. These include:
 * Temperature. Affects:
 * the burn speed of the propellant
 * the air density (and therefore the trajectory)
 * the expansion or contraction of the components of the rifle
 * mirages
 * Humidity. Affects
 * the air density
 * the burn rate of the powder
 * the expansion or contraction of the components of the rifle, especially natural materials like wood and leather
 * Air density. This is a function of temperature and humidity. Affects:
 * the projectile in flight
 * velocity of the projectile in the barrel
 * burn speed of the powder
 * Precipitation. Affects:
 * visibility
 * wet or moist ammunition/chamber or barrel can also affect the chamber pressure
 * the expansion or contraction of rifle components
 * Wind. Affects:
 * the lateral trajectory of the projectile (drift)
 * the velocity of the projectile, which affects both the lateral and vertical trajectory of the bullet
 * the temperature of the physical components of the weapon
 * visibility, e.g., blowing up dust or water

Factors Affecting The Mechanical Accuracy of the Rifle
When a rifle is fired the state of the rifle changes. Most of these changes are not perceptible to human senses, yet each of them has a real and definite effect on the accuracy potential of the rifle. For example when the rifle is fired the barrel flexes along its axis. This flexing is called whip. In order to obtain maximum accuracy this whip should be as consistent as possible each time the shot is fired. One way of achieving this is to minimize the whip. This can be done by stiffening the barrel, a condition usually achieved by adding more material to the barrel, i.e. making it heavier. In some cases the rifle is fitted with longitudinal flutes (ie grooves cut into the barrel along its length). These flutes increase the stiffness of the barrel, while reducing the weight - or at least reducing the weight compared to a solid barrel of similar stiffness. At the same time the barrel flexes along its length, the muzzle of the rifle moves, probably in a circle or oval, but possibly in some other pattern, across a plane at right angles to the bore. Maximum accuracy demands that the round leaves the muzzle at the same position on this plane every shot. Many factors affect the pattern described by the muzzle on this plane, the most controllable of which is the pressure exerted on the barrel by the receiver and the stock.

Application of Fire
Application of fire is the act of applying a group to a target.

I.e. is the ability of the combination of rifle, shooter and ammunition to place the group where desired.

Zeroing
Zeroing is the act of mechanically aligning the point of impact with the point of aim at a given range.

Holdover
Holdover is the practice of aiming at a point other than the desired point of impact (POI) to allow for factors such as range, weather, zero (in particular the range at which the weapons is zeroed, but also perhaps to allow for the fact that a weapon may have been zeroed for a person other than the current firer).

Advantages of Holdover

 * The holdover technique is fast to apply and does not require the shooter to break his shooting position.
 * Holdover is especially useful when the shooter needs to engage several targets at different ranges or a target whose range is changing, as the shooter is not required to break his position to adjust his sights for each range change.

Disadvantages of Holdover

 * The holdover may be difficult to apply at longer ranges, where the sights may need to be held several target heights above the point of aim. With a telescopic sight this can result in the target not being visible in the field of view.


 * The holdover, especially at longer ranges, requires a higher level of skill than sight adjustment.

Sight Adjustment
Sight may be adjusted to allow for lateral movement. Wind may affect the round and range, resulting in a vertical drop of the round in flight. By adjusting the sights at the time of firing, the need to apply holdover can be reduced or entirely eliminated.

Advantages of Sight Adjustment

 * Does not require as much experience of practice to master.
 * Allows the shooter to aim directly at the desired point of impact.

Disadvantages of Sight Adjustment

 * The shooter needs to memorize or have available (perhaps on a card or similar device) the characteristics of the sight adjustments and the trajectory for the ammunition rifle combination.
 * The shooter needs to keep track of how much adjustment is applied so that the sights can be re-adjusted back to zero when the current firing session is complete. For this reason, many firers choose not to adjust their sights unless the target is at such a long range that holdover is impractical, or if a first round hit is crucial, e.g., with a police or military sniper.
 * Requires the shooter to break their shooting position to re-apply their adjustments for each range over which a target is to be engaged.

Glossary

 * Application of fire - the act of superimposing a group on to a target
 * Beaten zone - the intersection of the cone of fire with the ground
 * Cone of fire - volume of space described by the outermost projectiles in a burst of fire.
 * Dangerous space - the area between first catch and first graze.
 * Enfilade - the application of the length of the beaten zone to the longitudinal axis of the target.
 * First catch - the first point where the trajectory of a projectile intersects with a target
 * First graze - the first point where a the trajectory of the projectile first intersects with the ground.
 * Grazing fire - fire where the trajectory is largely or approximately parallel to the ground
 * Group a measure of angular accuracy, defined as a series of three or more shots fired at the same POA, from the same position/hold.
 * Mean Point of Impact (MPI) - the center of a group, ignoring any obviously "pulled" or "jerked" shots.
 * Mechanical accuracy - the accuracy of a rifle or ammunition discounting as much as possible inaccuracies introduced by other components. E.g. when trying to gauge the mechanical accuracy for a rifle you might fire the rifle from a mechanical rest, using the same load of ammunition for each firing, and ideally under the same environmental conditions.
 * Plunging Fire - fire where the firer is higher than the target and therefore looks and fires down upon the target. Plunging fire results in a - small beaten zone not significantly larger than the cone of fire.
 * Point of Aim (POA) - the point at which the firer aims with sights
 * Point of Impact (POI) - the point on the target where the round impacts
 * Whip - the axial flexing of the barrel at firing.
 * Zero - the act of superimposing the point of aim with the point of impact at a given range.

The initial author of this page was formally trained in marksmanship in the Australian Army. Therefore the terminology and definitions on this page are strongly influenced by Australian and Commonwealth terminology. In addition the page has a military orientation. Some of the information may not be useful in a purely civilian context, however the basic terminology and techniques discussed should be helpful to any shooter.