We may earn revenue from the products available on this page and participate in affiliate programs. Learn more ›
The term “ballistic coefficient” (BC) has become a buzzword for the modern rifle shooter. It didn’t used to be talked about that much, but today cartridges are designed and rifles are built around bullets with a high BC. BC seems to be all anyone cares about anymore, but what exactly is it, and should hunters even care about it?
What is Ballistic Coefficient?
According to the NRA Firearms Sourcebook (2006), ballistic coefficient, “represents the bullet’s ability to overcome the air resistance in flight.” Brian Litz, noted long-range shooter and the author of Modern Advancements in Long-Range Shooting (2014), defines BC as, “the ability of a bullet to maintain velocity, in comparison to a ‘standard projectile.’” Regardless of the definition, because BC is an estimation and because it’s not a constant—it degrades with velocity loss—it’s best described as a very well-educated guess.
An entire book could be written about BC and the differences between G1 and G7 BC calculations. But what you need to understand is that when comparing two bullets of the same caliber and weight, launched at the same velocity, the bullet with the higher BC will get to the target sooner and with less drop and wind deflection. Also, with modern bullets, a G7 BC is more accurate than a G1 BC. It’s hard to argue that a higher BC is not a good thing but how good is it for hunters?
The primary function of a hunting bullet is to deliver optimal terminal performance. There are essentially three types of bullet behaviors with hunting bullets, which were detailed in my book Rifle Bullets for the Hunter (2006). You have penetrators which offer minimal deformation and high weight retention. Fragmenting bullets, that deform a lot and can shed a lot of weight, and finally, balanced bullets which sort of balance deformation and weight retention. While none of this has anything to do with BC, it has a lot to do with hunting, and high-BC bullets can fall within any of these three classifications.
Hunters should select hunting bullets based on the terminal performance first because you always want enough penetration, and the more a bullet deforms the more tissue it will damage. For example, the ideal bullet for a coyote will deliver quite different terminal performance than the ideal bullet for an elk. Ballistic coefficient plays a part in terminal performance, but probably not in the way you might think.
The Need for Speed
Bullets with a high BC do not go faster, they’re just slower to slow down. Let’s look at two 150-grain bullets fired from a 308 Winchester at the same velocity. The 150-grain Remington Core-Lokt has a BC of 0.314 and the 150-grain Tipped Core-Lokt has a BC of 0.415. The first chart shows the retained velocity of both from the muzzle out to 500 yards, and it illustrates the velocity retention advantage of the higher BC bullet.
Velocity retention is important because a bullet must impact with enough velocity to work as intended. Both these bullets need about the same impact velocity to upset, which is around 1600 fps. At 500 yards bullet upset with the standard Core-Lokt bullet is iffy, but with the Tipped Core-Lokt, it’s almost a guarantee. This is how BC influences terminal performance. (For your reference, cup-and-core bullets need to impact at least 1600 fps, bonded bullets at about 1800 fps, and mono-metal bullets work their best when impacting at 2000 fps or more.)
BC also reduces the time of flight, which in turn reduces the amount of time gravity and wind have to act on the bullet.
The second chart shows the difference in drop and drift in a 10mph cross-wind that you could expect from these same two loads. In this comparison, there’s not more than a few inches difference until beyond 300 yards.
Ultra-High BC Bullets
Let’s take the comparison to a different level by looking at an ultra-high BC bullet. You could say that BC is just another expression of how aerodynamic a bullet is, and to make bullets more aerodynamic they’re made longer. This often means they’re heavier. The problem with heavier bullets is that they cannot be started out as fast. Look at the results for the Remington 172-grain Premier Long Range load with a 0.522 BC. Even though it starts 200 fps slower than the Core-Lokt bullets, at 400 yards it’s going as fast as the Tipped Core-Lokt, and at 500 yards, it’s almost 300 fps faster than the standard Core-Lokt.
The heavier Premier Long Range bullet does not shoot much flatter than either of the Core-Lokt bullets but notice how much better it defies the wind. It will experience less wind drift from the muzzle all the way out to 500 yards, where it drifts substantially less than both. However, just as with any other bullet, a high BC bullet must still have enough velocity to promote bullet upset. In the case of the bonded, 172-grain Premier Long Range Speer Impact bullet, it needs to impact at around 1800 fps to deliver meaningful deformation.
High BC or Not
With these three loads, inside 300 yards there’s not enough difference to matter unless you’re shooting in a hurricane. At beyond 400 yards the standard Core-Lokt—low BC bullet—has slowed to the point bullet upset is questionable, but the other bullets should open out to 500 yards, and if you think you have any business shooting at a big game animal that far away, the Premier Long Range bullet will handle the wind better. But, because of its bonded construction, at 500 yards it’s reached its threshold impact velocity. So, beyond 500 yards the Tipped Core-Lokt with a moderate BC might be a better option.
Read Next: 5 Cartridges I’d Never Hunt Deer With
For the target shooter, time of flight, trajectory, and wind drift are very important. It’s why the 6.5 Creedmoor cartridge was designed for high BC bullets, it’s why 6.5 Creedmoor rifles have fast twist barrels, and it’s also why many hunters hate the praise the 6.5 Creedmoor gets. They know that with most modern rifle cartridges, inside 300 yards this BC business matters hardly at all.
Hunters should choose their load based on the terminal performance they need at the distances they intend to shoot. Then, they should select the highest BC bullet that will reliably deliver that performance and that will shoot well in their rifle. Sacrificing terminal performance in exchange for aerodynamics is like bear hunting with a greyhound dog vs a hound. You might get to the bear sooner, but the end result will not be pretty.