Chapter 1: EXTERNAL BALLISTICS As the bullet leaves the barrel, it faces 2 major external forces of mother nature: 1. GRAVITY - this force pulls down the bullet in flight, causing it to drop from the line of departure as it gains range. 2. AIR RESISTANCE - air friction due to the air density which slows down the bullet in flight. When the bullet loses velocity, the gravity more easily pulls it down. Those 2 forces cause the bullet to slow down and drop which resulting in a curve trajectory. Bullet trajectory solely depends on these 2 factors: 1. BALLISTICS COEFFICIENT (BC) - aerodynamic value of a bullet to retain its initial velocity while flying through the air (how well is the bullet to fly through the air without losing its velocity). This value depends on bullet shape and weight. High BC value means the bullet can reach farther without losing much velocity. BC value ranges from 0.1 – 1.0! 2. MUZZLE VELOCITY (MV) - the initial velocity produced inside the barrel. it depends on how well the powder can push the bullet. High velocity makes the bullet able to reach farther (so that's why we need high BC for the bullet to retain its velocity)
You totally gotta measure those 2 factors precisely because BC & MV will lead us to the 2 crucial Ballistic aspects in Long Range Shooting: 1) BULLET DROP
Bullet Drop solely depends on: A) Range The farther your target, the bigger your bullet drop! Distance will increase the bullet drop so range your target before shooting! Measure your range by using your laser range finder (click on “B” key)
B) Angle of firing
For a bullet to strike a target at a Slant Range (RS) and an incline of α , the rifle sight must be adjusted as if the shooter were aiming at a horizontal target at a range of RH = RS cos (α) where Slant range x Angle = Horizontal Range. So when shooting uphill/downhill, you must adjust your scope at horizontal range not the slant range! Under 15°, it doesn’t really matter! Above 15°, it matters! Aim at Horizontal range not Slant Range! Here’s the quick adjustment: 15° → adjust as if aiming at a 95% Slant Range 20° → adjust as if aiming at a 93% Slant Range 25° → adjust as if aiming at a 90% Slant Range 30° → adjust as if aiming at a 86% Slant Range 40° → adjust as if aiming at a 76% Slant Range 45° → adjust as if aiming at a 70% Slant Range 55° → adjust as if aiming at a 57% Slant Range 65° → adjust as if aiming at a 42% Slant Range C) Air pressure
Lower Air Pressure actually decreases the Air Density, and therefore decreases the drag so resulting in less Bullet Drop. Higher Air Pressure actually increases the Air Density, and therefore increases the drag so resulting in more Bullet Drop. Measure the air pressure by using the Kestrel 4500 (click on the “Scroll Lock” key)
D) Air temperature
Higher Temperature actually decreases the Air Density, and therefore decreases the drag so resulting in less Bullet Drop. Lower Temperature actually increases the Air Density, and therefore increases the drag so resulting in more Bullet Drop. Measure the air temperature by using the Kestrel 4500 (click on the “Scroll Lock” key) E) Ammo temperature Higher ammo temperature will increase the Muzzle Velocity and therefore decreases the Bullet Drop significantly. Lower ammo temperature will decrease the Muzzle Velocity and therefore increases the Bullet Drop significantly. Ammo temperature corresponds to Air Temperature. Measure the ammo temperature (air temperature) by using the Kestrel 4500 (click on the “Scroll Lock” key) F) Air humidity Higher Humidity actually decreases the air density, and therefore decreases the drag so resulting in less Bullet Drop. Lower Humidity actually increases the air density, and therefore increases the drag so resulting in more Bullet Drop. Measure the ammo temperature (air temperature) by using the Kestrel 4500 (click on the “Scroll Lock” key) G) Vertical Coriolis effect (earth rotation) When shooting east, the bullet drop decreases! When shooting west, bullet drop increases! Coriolis effect depends on your Latitude and Azimuth/Bearing (check your map “M” and compass “K”)
2) SIDEWAY DRIFT/WINDAGE Wind always makes the bullet deviate from its trajectory. In other words, bullet’s drifting to the left or right (sideways drift). Your bullet will drift in the direction of the wind. To compensate for this, you must aim into the wind, to the right or left.
Windage solely depends on: A) Wind direction Wind Direction will affect the mount of side drift! the angle of the wind determines the wind value. In other words, Wind Direction affects wind speed value. (click on “Shift+K”)
Types of wind: 1. HeadWind & TailWind (12 o’clock & 6 o’clock/0°) don’t matter too much but at farther range Headwind will slightly increase bullet drop and Tailwind will decrease bullet drop slightly. 2. CrossWind does matter coz it has the strongest effect on horizontal path of the bullet! types of Crosswind: a) 9 o’clock & 3 o’clock wind (90°) give full effect so Wind Speed x 1
b) 11 o’clock, 1 o’clock, 5 o’clock, & 7 o’clock (30°) give little effect soWind Speed x 0.5 c) 10 o’clock, 2 o’clock, 4 o’clock, & 8 o’clock (60°) give almost full effect so Wind Speed x 0.86 d) 45° wind give little effect so Wind Speed x 0.7
B) Wind speed Measure it with windmeter or Kestrel 4500 (click on “Scroll Lock” key)
or by observing the angle of heat waves/Mirage
C) Spin Drift (bullet rotation) Even in completely calm air, with no sideways wind at all, a spin-stabilized projectile will experience a spin-induced sideways component. For a right hand (clockwise) direction of rotation this component will always be to the right. For a left hand (counterclockwise) direction of rotation this component will always be to the left. At extreme long range (beyond 1000 m), spin drift increases significantly.
D) Horizontal Coriolis effect (earth rotation) When shooting north, the bullet deviates slightly to left! When shooting south, the bullet deviates slightly to right! Coriolis effect depends on your Latitude and Azimuth/Bearing (check your map “M” and compass “K”) After all those factors have been measured, you input them all onto your Atragmx (click on “Break” key) or your own real ballistics calculator
Chapter 2: SCOPE Because of external ballistic factors (Bullet Drop & Wind Deflection), point of aim(where you are aiming) is not going to be point of impact (where the bullet lands) so you always have to compensate for it using your scope There are 2 ways to compensate for the external ballistic factors: a. HOLDOVER To compensate for Bullet Drop, you can hold your reticle over the target. Just place your reticle above the target so the bullet will drop directly onto the target. In other words, the shooter is aiming higher than the target's position in the sight to allow for the bullet's drop during travel rather than adjusting the scope.This method is usually called Arkansas Elevation.
To compensate for Wind Drift, you can aim into the direction of the wind. You can aim to left or right, depending on which way the wind comes from. If the wind blows from the right, you aim to right. If the wind blows from the left, you aim to left. In other words, the shooter is aiming at a point horizontal to the target's position in the sight rather than adjusting the sight to compensate. This method is usually called Kentucky Windage.
b. SCOPE DOPING / SCOPE ADJUSTMENT Ideally, snipers want point of aim and point of impact to be exactly the same. So They line up these points by adjusting the scope (after all external ballistic factors been factored into the shot). Basically, scope adjustment is almost the same thing with Holdover! But instead of placing the reticle above the target & aiming into the wind, you actually adjust your scope optic so the optic lines up the point of aim & point of impact, as if you're aiming right at the target while in fact you're actually still doing a holdover. in other words, the scope helps you holdover the target. There are 2 types of scope adjustment (correlating with those 2 ballistic factors): 1. ELEVATION ADJUSTMENT Elevation Knob (the turret above your scope) → to dial it in, rotate it clockwise! to dial it out, rotate it counterclockwise! (click on arrow key “↑ ↓”) 2. WINDAGE ADJUSTMENT
Windage Knob (the turret on the right side of your scope) → to dial it in, rotate it clockwise! to dial it out, rotate it counterclockwise! (click on arrow key “← →”)
The scope reticle and the scope adjustment both work in Miliradian! To operate the scope reticle and scope adjustment, you must use Miliradian (Mil) as your angular measurement! Miliradian (Mil) is the unit of measurement being used in sniping/sharpshooting! We always use Mil because it’s so much better in measurement than degrees, thus more precise.
Just Remember, at 100 m, 1 Mil = 0,1 m (10 cm) & 0.1 Mil = 1 cm ! At 1000 m, 1 miliradian = 1 m (100 cm) & 0.1 Mil = 10 cm
Chapter 3: ADVANCED BALLISTICS QUICK TUTORIAL here let me sum it up for you: 1) input loadout parameter onto the ballistics solver. Open up the AtragMX (Break key) or use your own ballistics solver to input these: - Ballistics Coefficient (BC) - How aerodynamic the shape of bullet can overcome the air friction to retain its velocity (BC value ranging from 0 - 1 depending on what type of bullet you use) - Muzzle Velocity (MV) - Initial bullet velocity which always varies depending on the temp! MV will always change due to air temperature so better be careful... - bullet mass, bullet diameter, bullet length, - scope height, zero range, etc
2) measure the Air Density or Atmospheric Condition open up the Kestrel (Scroll lock key) & measure the Air pressure, Air Temp, humidity, then input them onto your solver
3) Range the target use your Rangefinder (B key)
4) measure the Angle of Firing open up the protractor (Ctrl+Shift+k) to measure the inclination angle, then input it on the solver
5) Spin drift & Coriolis effect the AtragMX won't show it so use your own ballistics solver (if you have lol) spin drift is due to barrel rifling twist, bullet length coriolis is due to ToF, latitude, and azimuth but those won't matter too much unless you're doing extreme long range shooting
6) do the Wind Reading get wind direction (Shift+k) measure Uprange Wind through kestrel measure Downrange Wind through Mirage (but you can barely see it lol) input them onto your solver
7) let the ballistics solver do the math and come up with the firing solution (drop & drift in Mil or MoA)
8) go prone and deploy your rifle on a bipod to steady your aim
9) to compensate for the drop & drift, you can hold it off (aim above the target & aim into the wind) or dial it in on the scope adjustment
10) Elevation adjustment is up & down arrow key, Windage adjustment is right & left arrow key i prefer dialing the elevation and holding the windage (since wind is changing like crazy lol XD)
11) relax, hold your breath (right mouse button), then pull the trigger gently to send it! BAANNGG!!!
you're welcome :) hope this helps ;) good shooting! ^_^ Vekongmaster
