Heavy Bullet Drift Myth Busted
The heavy bullet drift myth continues to fool many hunters. Heavier bullets do NOT always reduce wind deflection. In some cases they make it worse.
Higher B.C. is the real solution. Weight is just one part of B.C.
Form factor (shape) is the other critical part of high bullet B.C., and diameter is part of form factor. A narrow bullet in any given shape has a higher B.C. than a wider (larger caliber) bullet.
Maximum velocity helps minimize wind deflection.
Photo shows big round nose and fat nose bullets beside a spire point to emphasize form factor in heavy bullet drift myth.
The Truth About The Heavy Bullet Drift Myth
A reader of ronspomeroutdoors.com recently wrote that he’d “upgraded” from several 6.5mm cartridges, including a 264 Winchester, to a 270 Winchester and 7mm Remington Magnum in order to combat wind deflection. Another victim of the heavy bullet drift myth.
Bullet weight by itself doesn’t beat the wind. Higher velocity and, more importantly, high Ballistic Coefficient bullets beat the wind. This is why the right 75-grain .224 bullet fired 3,000 fps deflects less in a given wind than a .308 bullet twice as heavy. Let’s compare a Hornady 75-grain .224 ELD-Match bullet to a Nosler CT Ballistic Silvertip 150-grain round nose .308 bullet. (The Nosler bullet is tailored for 30-30 velocities, but we'll boost it with a 30-06 to reach 3,000 fps.) We’ll zero both at 200 yards and shoot them at 3,000 fps. If the "heavier bullet theory is correct, the 150-grain should deflect a lot less than that little 75-grain. Notice the different B.C. ratings of each bullet under the red Input Variables title.
Image is a chart listing the drop, drift and energy levels of a 75-grain bullet fired in a right angle wind, knocking holes in the heavy bullet drift myth.
Big surprise, huh? Heavy bullet drift myth exposed! Not only does the heavier bullet drift twice as much as the lighter one, it even drops more. And at 500 yards the puny little 75-grain .224 bullet is carrying more energy! Lots of myth busting here. (Learn more about bullet performance on this post.) But the main point to soak in is that doubling a projectile’s weight does not make it deflect less in the wind if its shape is ballistically inefficient. B.C. matters. Boy, does it matter. Please understand: weight or bullet density is a part of B.C., but form factor or shape is, too. So is diameter. Combine all -- narrow (small caliber,) dense material (lead instead of copper, gold instead of lead,) and a long, sharp, extremely tapered nose and boat tail -- and you maximize B.C. and minimize air drag.
Why the Heavy Bullet Drift Myth Persists
Acceptance of the old heavy bullet drift myth is understandable for two reasons: common sense and decades of gun writers advocating heavier bullets to beat the wind. The writers were partially right. The common sense reasoning was dead wrong. I’ve been guilty of both.
What most of the writers were saying was that if you were shooting, say, a 150-grain spire point in your 30-06, you would get less wind drift if you stepped up to a 180-grain spire point. What they often failed to emphasize was that the bullet’s shape or form had to remain fairly constant. As the ballistic tables above show, going from a spire point to a round nose doesn’t work.
As for common sense, well, life experience makes it rather obvious that the wind is going to blow a light bullet farther off course than a heavy bullet. Heck, set a ping-pong ball and a golf ball on a porch railing on a windy day and guess which one blows off first.
But bullets in flight are not affected quite that way. It’s not just the wind moving the projectile right or left. It’s also a product of head winds slowing the bullet. Atmospheric drag slows the bullet’s progress. This means it remains in the air longer to travel a specific distance. That increases the time wind has to move it.
But that’s still not the end of the story. According to some, cross winds don’t just carry bullets off course — they give bullets additional vectors and momentum. A bullet nudged slightly right by a 10 mph wind coming from its left is subsequently angling ever farther right as it moves downrange. Even if the wind quits, the new angle continues directing the bullet off line-of-sight. A fraction of an inch shift near the muzzle becomes, thanks to that new vector and angle of departure, several inches downrange.
Alternate Wind Deflection Theory Might Clear or Complicate Bullet Drift Myth
There’s another theory I’m still wrestling with that claims the bullet aligns itself with the wind much like a weather vane. It positions its nose with the combined air pressures (drag) of the headwinds created by its own velocity plus any crosswind component. This seems reasonable, but my somewhat limited and challenged intellect suggests this would point the nose into the wind, resulting in the bullet progressing slightly into the wind rather than away from it. Wouldn’t this result in a deflection into the wind? Unless the bullet merely orients itself into the combined air pressures while moving downrange slightly quartering toward the target. I’m confused. If you’d like to figure it out for me, check out this video.
Regardless exactly how crosswinds cause bullet deflection, you can see the effect easily. Just shoot different weight/shape/B.C. bullets at paper targets in big crosswinds. The resulting holes should convince you that increasing bullet mass alone does not solve the problem -- and without a good form factor, can even make it worse. Be an informed shooter. Don't fall for the heavy bullet drift myth until you've tested it for yourself.
Veteran outdoorsman, handloader, and author Ron Spomer has put venison on the table with bullets weighing as much as 500 grains and as little as 55 grains, but rarely at long range in high winds. His ultimate secret for beating wind deflection? Sneak closer.
