Ballistic solution example: calculation - Guide - UNITAF Force Manual (FM)




Ballistic solution example: calculation



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FM/BG-622.V1.10 - Ballistic solution example: calculation

Preparation

Sgt McShooty is deployed as a Spotter (Manual) on a Honeybadger. He aims for to be able to assemble a ballistic solution in any conditions, so he prepares calculations for the operation.

His sniper is using the M24 SWS and they will only be using the M118 LR bullet. Prior to operation start, he looks at an ATragMX to record time of flight for his given atmospherics.

Target RangeTime of Flight
400m0.61s
500m0.79s
600m0.99s
700m1.20s
800m1.43s
900m1.68s
1000m1.95s

 

Target requirements

In operation, Sgt McShooty identifies an OPFOR machine gunner engaging a friendly squad. A follow up shot will not compromise any objectives, so he can disregard most Tertiary Components entirely.

In addition to this, he is presented with fairly typical shot conditions, as:

  • There is no wind present
  • The target is stationary
  • He is not firing at a steep incline
CategoryBallistic ComponentDirection of Deflection
PrimaryBullet Drop (composite)Vertical
PrimaryMoving TargetsHorizontal
PrimaryCrosswindsHorizontal
SecondaryInclined ShootingVertical
SecondarySpin DriftHorizontal
SecondaryCoriolis EffectHorizontal
TertiaryEotvös EffectVertical
TertiaryHeadwinds & TailwindsVertical
TertiaryAir Density changesVertical

 

Ballistic solution assembly

Bullet drop

Sgt McShooty ranges his target at 800m according to FM/BG-522 - Milliradians: Mil-relation formula

Looking at his range card, he finds a bullet drop adjustment of 9.1 mils.

 

Spin drift

He uses the Spin Drift formula to calculate horizontal deflection according to FM/BG-558 - Spin drift: calculation:

((SG * Time of Flight ^ 1.83) / Distance) * 1000 = Spin Drift in MRADs

((.0759 * 1.43 ^ 1.83) / 800) * 1000 = .18 MRADs

Because his barrel twist is right hand, his bullet will deflect .18 MRADs to the right.

 

Coriolis effect

He uses the Horizontal Coriolis Effect formula to calculate horizontal deflection according to FM/BG-553 - Horizontal Coriolis force: calculation:

cos(latitude°) * (Time of flight in seconds) * .072 = Horizontal deflection in MRADs

cos(35°) * (1.43) * .072 = .08 MRADs to the Right

 

Final ballistic solution

Sgt McShooty adds his two horizontal components together for a total of .26 MRADs to the right.

Because his deflection is low and to the left, he tells his sniper to adjust up and to the right

Final Ballistic Solution: 9.1 mils up, 0.26 mils left

Published by Sgt Jochem on 05/07/2024 at 21:28
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