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Tuesday, January 31, 2017

The Science behind shooting: Velocity and BC: Hornday .308 168 GR



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In my last article we covered selecting the right caliber for your shooting application and what factors go into making that decision. Now that caliber selection is complete the next thing to take into consideration is getting the most out of your rifle.

The ballistic coefficient  (BC) or the bullet and the velocity of the bullet play a large factor in your  accuracy and speed at extended ranges. I would like to compare 4 different factory rounds for this article. These factors are still just as important if you handload your rounds.

The rounds I will be using for this article are the following:
Hornady .308 168 GR A-MAX: G1 BC: .475, velocity at the muzzle: 2700 FPS
Hornady .308 168 GR A-MAX Superformance: G1 BC: 475, velocity at the muzzle: 2840 FPS
Hornady .308 168 GR ELD Match: G1 BC .523, velocity at the muzzle: 2700 FPS
Hornady .308 168 GR ELD Match Superformance: G1 BC .523, velocity at the muzzle: 2840 FPS

All velocity information is taken from Hornady who uses a 24” barrel and I will be using the G1 BC of each round. My Altitude density is -1060 and my wind value is 90° at 4.47 MPH. All data is run through Applied Ballistics Mobile App.



Round
300 Yard Drop
500 Yard Drop
700 Yard Drop
900 Yard Drop
1000 Yard Drop
AMAX
14.6"
59.7"
147.6"
296.4"
401.3"
AMAX Super
12.8"
52.9"
131.0"
263.0"
356.0"
ELD Match
14.2"
57.7"
140.5"
277.6"
372.7"
ELD Match Super
12.5"
51.1"
124.8"
246.4"
330.8"
Round
300 Yard Drift
500 Yard Drift
700 Yard Drift
900 Yard Drift
1000 Yard Drift
AMAX
2.89"
8.45"
17.69"
31.3"
39.85"
AMAX Super
2.56"
7.38"
15.35"
27.1"
34.52"
ELD Match
2.43"
6.93"
14.3"
25.03"
31.75"
ELD Match Super
2.27"
6.44"
13.28"
23.26"
29.57"



It should come to no surprise that the round with the highest BC and Velocity out performed all the other rounds and that the round with the lowest BC and velocity was affected more by the wind and dropped at a faster rate. This relates to us as shooters because the more a bullet drops or is affected by wind, the more adjustments we need to dial in on our scopes to compensate. More adjustments means more time in between shot, and leads to a higher chance of error while dialing in adjustments.

 

Hornady 168 GR A-MAX

Hornady 168 GR A-MAX Superformance








Hornady 168 GR ELD Match








Hornady 168 GR ELD Match Superformance

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