You Will Shoot Your Eye Out

Ballistic Coefficient (BC) is a mathematical measure of a bullet’s ability to overcome air resistance in flight. Think of it as an aerodynamic efficiency rating: a higher BC means the bullet cuts through the air better, retains its velocity longer, and drifts less in the wind.

If you are shooting at 100 yards, BC doesn’t matter much. But if you want to shoot past 300 yards, compete in PRS, or hunt ethically at extended ranges, Ballistic Coefficient is the single most important number printed on your box of ammunition.

Here is exactly how Ballistic Coefficient works, the difference between G1 and G7, and how to use it to hit your target.

How Does Ballistic Coefficient Work? (The Physics)

Once a bullet leaves the muzzle, two primary forces act upon it: gravity (which pulls it down) and aerodynamic drag (which slows it down). Gravity is a constant, but drag is a variable that depends entirely on the bullet’s design.

If there is wind outside and the bullet is traveling a notable distance, wind is another force acting on it.

To calculate how well a bullet fights drag, ballisticians use a simple formula: BC = SD / i

• SD (Sectional Density): This is the bullet’s weight relative to its diameter. For a given caliber, a heavier bullet will have a higher Sectional Density. Heavy objects carry more momentum and are harder to slow down.
• i (Form Factor): This is the aerodynamic shape of the bullet. A long, pointy bullet with a boat-tail has a very low (efficient) form factor. A short, flat-nosed bullet has a high (inefficient) form factor.

The Takeaway: To get a high Ballistic Coefficient, you need a heavy, long, and pointed bullet. A light, short, and flat bullet will always have a low Ballistic Coefficient.

High BC vs. Low BC: What’s the Difference on the Range?

Many beginners mistakenly believe that muzzle velocity is the most important factor for long-range shooting. It isn’t. A slower bullet with a high BC will almost always outperform a faster bullet with a low BC at distance.

To prove this, let’s compare two common .308 Winchester loads at 500 yards: a traditional 150gr Flat Base Soft Point (Low BC) and a modern 175gr Sierra MatchKing (High BC).

Metric	150gr Flat Base Soft Point (Low BC: ~0.314 G1)	175gr Sierra MatchKing (High BC: ~0.505 G1)
Muzzle Velocity	2,820 fps	2,600 fps
Velocity at 500 Yards	1,520 fps (Losing speed fast)	1,750 fps (Retains speed)
Energy at 500 Yards	770 ft-lbs	1,190 ft-lbs (+54% more energy)
Bullet Drop at 500 Yds	-52.5 inches	-58.2 inches*
Wind Drift (10mph at 500 Yds)	28.5 inches (Blown off target)	18.4 inches (Cuts the wind)

*Note: The heavier 175gr bullet has slightly more drop at 500 yards because it starts with a slower muzzle velocity. However, because of its high BC, it retains energy far better and drifts 10 inches less in the wind—making it vastly superior for long-range precision. Calculated using BallistX.

As you can see, wind drift is the real killer at long range. A high BC bullet acts like a dart cutting through the wind, while a low BC bullet acts like a parachute being blown off target.

G1 vs G7 Ballistic Coefficient: What’s the Difference?

If you look at a box of modern precision rifle bullets, you will often see two different Ballistic Coefficient numbers listed: a G1 BC and a G7 BC.

To understand the difference, you need to know how BC is calculated. Ballistic Coefficient isn’t just an arbitrary number; it is a comparison. It compares your bullet’s flight to the flight of a “Standard Projectile.” The problem is that bullets come in very different shapes, so ballistic engineers use different “Standard Projectiles” (drag models) to get an accurate comparison.

The G1 Standard (The Old School Bullet)

The G1 drag model is based on a standard projectile that looks like an old artillery shell. It has a flat base and a relatively blunt, short nose.

• When to use G1: You should use the G1 BC if you are shooting flat-based bullets, pistol bullets, muzzleloader projectiles, or blunt lever-action bullets (like a .30-30 flat nose).
• The flaw with G1: Because a G1 standard projectile is so un-aerodynamic, its drag changes drastically as it slows down. If you use a G1 BC for a modern long-range bullet, the calculator has to constantly adjust the BC based on velocity, which introduces math errors at extended distances.

The G7 Standard (The Modern Precision Bullet)

The G7 drag model is based on a standard projectile that looks like a modern long-range rifle bullet. It has a long, pointed nose (ogive) and a tapered boat-tail base.

• When to use G7: You should use the G7 BC for any modern, pointy, boat-tail bullet. This includes almost all bullets used in PRS, NRL Hunter, and modern long-range hunting (e.g., Hornady ELD-M/ELD-X, Berger Hybrids, Sierra MatchKings).
• The advantage of G7: Because the G7 standard projectile actually matches the shape of modern bullets, the drag remains much more constant as the bullet slows down. This gives you significantly more accurate drop data in your ballistic calculator at 600+ yards.

The Golden Rule: If the bullet has a boat-tail, use the G7 BC. If it has a flat base, use the G1 BC. (Do not let the larger G1 number trick you—they are simply on different mathematical scales).

Does Ballistic Coefficient Change with Velocity?

Yes. Ballistic Coefficient is not a static, magical number. As a bullet flies downrange, it loses velocity. When a bullet slows down and approaches the transonic barrier (around 1,200 fps), the way air flows around it changes dramatically, which alters its drag profile.

This is why advanced weather meters and solvers (like a Kestrel with Applied Ballistics) use custom drag models rather than relying on a single static BC number. However, for 99% of shooters engaging targets inside of 1,000 yards, using an accurate G7 BC in a quality ballistic app is more than enough to get first-round impacts.

How to Use BC to Hit Your Target

Knowing your bullet’s Ballistic Coefficient is useless if you don’t do the math. You cannot calculate wind drift and bullet drop in your head.

To get your exact scope holds, you need a ballistic solver. Input your bullet’s G7 BC, your muzzle velocity, and your current environmental data (altitude, temperature) into our BallistX Calculator. The physics engine will run the math and tell you exactly how many MOA or MRAD to dial on your scope to hit your target.

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