Bullets vs. Wind

Bullets vs. Wind

Wind is the varmint shooter's greatest enemy, and the search for better "wind-bucking" bullets is never-ending.

If you've embarked on that search, be sure not to confuse a bullet's "wind resistance" with its "air resistance."


In flight, bullets are affected by three separate forces: gravity, air resistance and wind. Gravity pulls down on the bullet, causing it to drop below the line of sight. Air resistance (or "drag") slows the bullet with a force proportional to the square of the velocity. Wind makes the projectile drift from its normal still-air trajectory.



There are two key elements to understanding a bullet's susceptibility to wind drift. The first is its ballistic coefficient (BC), which combines the air resistance of the bullet shape (the drag coefficient) with its sectional density (the ratio of its frontal surface area to bullet mass), and is expressed by a figure providing the ratio of its ballistic efficiency compared to a standard theoretical reference projectile.

Sporting bullets have BCs in the range 0.12 to slightly over 1.00, with 1.00 being the most aerodynamic and 0.12 being the least. Bullets with higher ballistic coefficients have better air resistance, and the deceleration a bullet will experience due to drag is proportional to its BC.


In technical terms, wind drift is caused by drag. It is not, as is commonly thought, caused by wind pushing on the side of the bullet. Drag makes the bullet turn into the wind, keeping the center of air pressure on its nose.


This causes the bullet nose to angle into the wind and the base to be angled downwind. Since drag is the force slowing the bullet against the resistance of the air, the effect is to make it drift from its linear path in the downwind ("backward") direction. The greater the bullet's drag, the more it will drift.

Headwinds or tailwinds have similar but less obvious drag effects. A headwind will slightly increase the velocity of the bullet relative to the air it is passing though, which will increase the amount of drag and corresponding bullet drop.

A tailwind will reduce the drag and the bullet drop. In the real world, pure headwinds or tailwinds are rare since wind seldom is constant in force and direction and normally interacts with the terrain it is blowing over.

The second key element in a bullet's susceptibility to wind drift is its velocity. Here, unlike the complex physics of drag coefficients, the issue is simple. The longer the time any bullet is exposed to wind while in flight to the target, the more it will drift; the faster it gets there, the less it will drift.

While it is also true that drag increases as velocity increases, if you use bullets having high BCs to begin with, the benefit of the reduced flight time will outweigh any additional drag effect.

If you are seeking the maximum in wind resistance for varmint shooting, you need to pick the bullet with the highest ballistic coefficient (least drag) you can find for your cartridge of choice and push it to the highest velocity possible while maintaining the accuracy you need.

Recommended for You

Smith & Wesson's M&P15 SPORT II OR rifle with Crimson Trace CTS-103 optic will be on display at the Smith & Wesson Booth at the 2019 NRA Show. MSR

M&P15 SPORT II Rifle Available with CTS-103 Optic

Rifle Shooter Digital Staff - April 23, 2019

Smith & Wesson's M&P15 SPORT II OR rifle with Crimson Trace CTS-103 optic will be on display...

For decades, things were quiet on the .22 centerfire front. Starting in 2017, shooters were offered not one but two hot new centerfire .22 cartridges. First out of the gate was the .22 Nosler, followed by the Federal .224 Valkrie. Ammo

.22 Nosler vs .224 Valkyrie

Brad Fitzpatrick - May 02, 2019

For decades, things were quiet on the .22 centerfire front. Starting in 2017, shooters were...

Announced in 1958, the .264 and .338 Winchester magnums hit the market in 1959 amid one of the biggest media blitzes the industry had seen. Both were introduced in “new” versions of Winchester's beloved Model 70. Ammo

.264 and .338 Magnum - Winchester Twins

Craig Boddington - May 24, 2019

Announced in 1958, the .264 and .338 Winchester magnums hit the market in 1959 amid one of the...

See More Recommendations

Popular Videos

Gun Clips with Joe Mantegna - BULLPUPS

Gun Clips with Joe Mantegna - BULLPUPS

Joe Mantegna talks about the origins of Bullpups.

Hornady 6MM Creedmoor

Hornady 6MM Creedmoor

Tom Beckstrand and Neal Emery of Hornady highlight the 6MM Creedmoor ammo.

All About .300 Blackout

All About .300 Blackout

The .300 Blackout is here to stay, and we take some time to look at new technology surrounding this cartridge. Next, we pit subsonic rivals against each other before stretching the legs of this CQB round out to 600 yards from a short 9-inch barrel.

See more Popular Videos

Trending Stories

Some history and reloading recipes on five popular .17-caliber cartridges, including the .17 Ackley Hornet, .17 Hornady Hornet, .17 Mach IV, .17 Remington Fireball and .17 Remington. Reloading

.17-Caliber Reloading Data and History for 5 Cartridges

Layne Simpson - June 05, 2019

Some history and reloading recipes on five popular .17-caliber cartridges, including the .17...

Nosler pairs its M48 action with a new Proof Research carbon-fiber barrel for a high-tech long-range rifle you can actually carry: the Nosler Model 48 Long Range Carbon. Bolt-Action

Review: Nosler Model 48 Long Range Carbon

Layne Simpson - March 13, 2019

Nosler pairs its M48 action with a new Proof Research carbon-fiber barrel for a high-tech...

The Hi-Point 10mm carbine, technically the 1095 TS, sports a 17.5-inch barrel, is 32 inches long and weighs seven pounds empty. Semi-Auto

Review: Hi-Point 1095 TS 10mm Carbine

James Tarr - April 04, 2019

The Hi-Point 10mm carbine, technically the 1095 TS, sports a 17.5-inch barrel, is 32 inches...

See More Stories

More Ammo

In this Cartridge Clash, Brad Fitzpatrick pits the .270 Win. against the .270 WSM. Ammo

.270 Win. vs. 270 WSM

Brad Fitzpatrick - March 04, 2019

In this Cartridge Clash, Brad Fitzpatrick pits the .270 Win. against the .270 WSM.

The RifleShooter staff put together their gift guide for the upcoming holiday season, with products from SIG, Browning, Leupold and many more. Accessories

RifleShooter Holiday Gift Guide (2019)

J. Scott Rupp

The RifleShooter staff put together their gift guide for the upcoming holiday season, with...

SIG SAUER, Inc. introduced its newest 300BLK ammunition ' the 120gr supersonic 300BLK SBR Elite Copper Duty load, specifically designed for short barrel rifles. Ammo

SIG SAUER Introduces 120gr Supersonic 300BLK SBR Elite Copper Duty Ammunition

Rifle Shooter Online Editors - February 12, 2019

SIG SAUER, Inc. introduced its newest 300BLK ammunition ' the 120gr supersonic 300BLK SBR...

See More Ammo

GET THE MAGAZINE Subscribe & Save

Temporary Price Reduction.

SUBSCRIBE NOW

Give a Gift   |   Subscriber Services

PREVIEW THIS MONTH'S ISSUE

GET THE NEWSLETTER Join the List and Never Miss a Thing.