Zeroing your rifle
By Tim Davies of Premier Shooting Experiences
Holding her steady
The fundamental to zeroing, is to be stable. This often means using a bench rest or a bipod and a beanbag or rabbits ears sack under the butt. This will make it clear in your own mind that there is no inherent problem with the rifle or scope. If you are steady and the group is wide, then this shows that the poor shooting was down to the equipment.
This is the bread and butter of all shooting. If you can’t group you can’t zero, therefore if you can’t zero you can’t hit the target.
1 inch group at 100yds is the normal benchmark for sporting riflemen.
Remember your (ESA) Expected Scoring Area)
THEORY OF THE GROUP
One of the subjects that must be thoroughly understood is the theory of the group. This theory establishes that: When a series of shots (not less than 3) are fired from a rifle at the same point of aim, they will seldom, if ever, pass through the same hole in the target. The pattern produced on the target is known as a group. This theory also provides a simple rule, which, though not strictly accurate, states that the size of the group will increase proportionally to the range fired at, (i.e. 100mm group at 100 m will equal 200mm at 200m). The final point is that a rifleman’s grouping capacity is also a measure of their shooting ability.
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 (encouraging 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 groups.
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 and 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.
FACTORS AFFECTING THE GROUP
There are three factors which contribute to the group size (without considering light, wind or weather):
a. The ammunition. Ammunition is generally good and variations can be ignored for practical coaching purposes. It is generally produced in large lots and a random selection is taken from each lot to test for accuracy by firing a certain number of 20 shot groups. A group size is directly proportional to the number of shots fired. The increase is rapid to start and grows more slowly as more shots are added. The distribution of shots within the group is random and cannot be predicted or controlled by the soldier. The true MPI and zero of the system cannot be discovered until a fair number of shots have been fired;
b. The Rifle. Factory tests establish that a rifle will not put all shots through the hole, even when fired from a mechanical rest;
c. Human error by the rifleman. When a rifle is fired by the rifleman the following can be expected:
(1) The group size will be determined by how well the soldier observes the marksmanship principles;
Know how your scope works, and know your ballistics
Target analysis is the method of determining the soldier’s faults by examining the bullet holes on the target. The instructor should discuss each group with the student and explain the reason for imperfect groups.
The procedure for conducting target analysis is as follows:
a. Draw a rectangle enclosing all five shots with the sides of the rectangle parallel to the target;
b. Draw another rectangle enclosing the four most closely clustered shots;
c. The larger rectangle is the Actuality Group and shows the soldier’s actual ability at the present time;
d. The smaller rectangle is the Capability Group and indicates the riflemanspotential; . This determines the amount of coaching necessary before the soldier’s potential is realized
A vertical group indicates good trigger control but poor elevation, one or a combination of the following, are at fault:
a. Varying position of butt on the shoulder;
b. Low vertical triangle;
c. Failure to focus on front sight (iron) or aiming post (optical);
d. Incorrect or varying eye relief;
e. Lack of aiming precision;
f. Sight picture varied;
g. Faulty pre-firing breathing;
h. Position of left (forward) elbow wrong;
i. Varied backward pressure;
j. Varied head pressure; and/or
k. Poor follow through.
A horizontal group indicates good elevation and poor trigger control, any one, or a combination of the following, are at fault:
a. High vertical triangle;
b. High right shoulder;
c. Wandering front sight;
d. Holding the rifle with muscular effort instead of resting on the bone;
e. Jerking the trigger;
f. Hurrying the trigger squeeze;
g. Moving the right elbow;
h. Varying chin pressure;
i. Lack of aiming precision;
j. Faulty automatic alignment;
k. No stability of position
We are totally steady, but lets find out exactly what is going on on the target.
PERFECT TRIGGER CONTROL
1. Get into the Correct Shooting Position for the conditions at hand, and Get Comfortable. Make sure the Rifle is on a Suitable Rest (bipod, rear bag, shooting sticks, etc.)
2. Get your Scope Dialled In and On Target, and Get a Good Sight Picture.
3. Pull the butt of the rifle firmly into the shoulder, and hold it there. (Finger Off Trigger) Keep the Cross-hairs of the Scope Fixed on that Specific Point on the Target. Take the SAFETY OFF!
4. Get your Breathing Under Control, Slow and Steady. Breathe in Deeply, Exhale, Letting Half Out and Hold.
5. As you keep your mind and your eye focused through the scope on that specific target point; With the tip of the pad of your index finger placed on the "sweet spot" of the trigger, begin to Slowly Squeeze the Trigger straight back without stopping, in one steady and fluid movement.
6. Keep Your Eye(s) Open, as the shot breaks, and Concentrate on where the cross-hairs are on the target as the hammer falls. The Shot should “Feel” Good!
7. As soon as that shot breaks, continue to Keep a Rear-ward pressure on the Trigger, and the same grip on the rifle, and same body position as much as you can through the recoil of the rifle. This is called “Follow-Through”.
8. Strive to keep your grip on the rifle, your head position and cheek-weld on the stock; Looking through the Scope to SEE Your HIT on the Target. The goal is repeatable consistency, time after time, shot after shot.
9. Practice Perfect Trigger Control by Dry-Firing Drills, alone, in a low lighted room, with no distractions. Also use a "Snap-Cap" style dummy round to Protect the Firing Pin as you dry fire! DOUBLE CHECK to Insure Your Weapon is EMPTY and Pointed in a SAFE Direction. Perform 50 repetitions, practice on your technique. Get a feel for your trigger, and burn that feeling into your mind and muscle memory.
Look through the scope and know where the cross-hairs are on the target as the shot breaks. Part of calling the shot is being able to SEE the HIT and Admitting to Yourself if you flinch, or if you jerk the trigger. You must practice to control your body and Resist Flinching; this is where muzzle breaks help. You must eliminate any and all movement of the rifle as the hammer falls and the shot breaks. When practicing trigger control, the more times You Can "Honestly Call The Shots That Are Good", and it is Reflected on the Target paper, or the Steel Gong, the Better Long-Range Marksman You Will Become!
The importance of Trigger Control cannot be overstated. The jerking, slapping, incorrect finger position, any side movement on the trigger will show. Your Concentration will be on Making your Breathing, Grip, Sight Picture, Trigger Squeeze, and Follow Through "Flow In Unison". The only way to Achieve Smaller Groups, and Hit the Steel Plate at Distance is to Practice; and learning how to Call Your Shots by Keeping your Eye(s) Open.
Keep a diary of all shots and weather / wind conditions This shooting diary becomes your “bible”
Just to stress the position of your support arm (Sometimes referred to as the pillar or pivot and the tightness and position of the sling on that arm is critical for the stability of the rifle, and one of the key elements in adhering to the Marksmanship Principles.