Understanding the apex of your bullet's flight path changes how you hit targets at extended ranges. The maximum ordinate trajectory chart tracks the highest vertical point a projectile reaches above the line of sight between the muzzle and the target. For shooters running a standard 168-grain projectile—frequently found in .308 Winchester loads like the Sierra MatchKing or Hornady A-Max—knowing this peak prevents under-holding or missing over low-hanging obstacles.
When you fire a round, gravity immediately pulls it downward, but muzzle velocity forces the barrel to point slightly upward relative to the target line. The bullet crosses the line of sight on its way up, peaks at the maximum ordinate, and crosses the line of sight a second time at your zero distance. Mastering this curve allows precise adjustments for clearing terrain features and dialing precise long-range drops.
What is Maximum Ordinate and Why It Matters
Maximum ordinate isn't just an abstract metric for ballistics nerds. It defines the clearance window of your projectile. If you're shooting across a canyon or under low tree branches, knowing the exact height of the apex ensures you don't clip an intervening obstruction.
For a typical 168-grain .308 projectile leaving the muzzle at roughly 2,700 feet per second (fps) with a 200-yard zero, the apex doesn't happen right in the middle. Because drag decelerates the bullet constantly, the peak occurs slightly past the halfway point—usually around 105 to 115 yards downrange. At this peak, the bullet travels roughly 2.0 to 2.3 inches above the line of sight before gravity pulls it back down toward your zero.
If you zero your rifle at 100 yards, the trajectory behaves differently. The peak happens closer to 60 yards, rising less than an inch above the crosshairs before plunging steeply past 200 yards. Understanding these numbers prevents the common mistake of assuming a flat line of flight.
Real-World Ballistics for 168-Grain Loads
The 168-grain weight class sits in a sweet spot for medium-caliber rifles. It balances sectional density with a high ballistic coefficient (BC), typically ranging from .400 to .475 depending on whether you shoot a hollow point boat tail (HPBT) or an advanced polymer tip.
Let's look at how a standard 168-grain load travels when zeroed at 200 yards:
- Muzzle (0 yards): -1.5 inches (accounting for scope height over bore)
- 50 yards: +1.2 inches (climbing toward apex)
- 100 yards: +2.0 inches (approaching peak height)
- 115 yards (Approximate Apex): +2.2 inches (Maximum Ordinate)
- 150 yards: +1.4 inches (descending)
- 200 yards: 0.0 inches (second zero crossing)
- 300 yards: -8.4 inches (significant drop begins)
Notice how the bullet stays within a tight three-inch vital zone from the muzzle out to about 230 yards. This point-blank range calculation relies entirely on the maximum ordinate staying low enough to keep hits inside a game animal's vitals without touching turret adjustments.
How Environmental Factors Shift the Apex
Your maximum ordinate isn't a fixed constant. Air density, altitude, temperature, and muzzle velocity alter the flight path significantly.
If you load your 168-grain rounds hot to achieve 2,800 fps instead of 2,700 fps, the bullet flattens out. A higher velocity means the bullet reaches the target faster, spending less time under the continuous pull of gravity. Consequently, the maximum ordinate drops slightly in height and moves further downrange because the initial upward angle of the barrel can be reduced.
Conversely, shooting in high-density altitude (cold, damp weather at sea level) increases atmospheric drag. The projectile slows down faster in the first hundred yards, causing the trajectory arc to hump slightly higher. While this change might only amount to a fraction of an inch, long-range precision shooters account for it when calculating obstacle clearance.
Common Mistakes When Reading Trajectory Charts
Shooters often misinterpret ballistic tables because they ignore key baseline variables. Avoiding these errors saves ammunition and frustration at the range.
- Ignoring Scope Height: Many generic charts assume a standard 1.5-inch scope height. If you run a modern chassis with a 2.0-inch or 2.5-inch optical centerline due to large objective lenses or night vision mounts, your near-range drops and maximum ordinate values shift.
- Confusing Apex with Midpoint Distance: Do not assume the highest point of the trajectory is at exactly 50 percent of your zero distance. Air resistance disrupts symmetry, pushing the peak further downrange.
- Trusting Raw Software Outputs Blindly: Ballistic calculators provide estimates based on standard drag models. Always verify your drop data and maximum ordinate calculations with real-world chronograph and target testing at varying yardages.
Frequently Asked Questions
Does bullet construction change the maximum ordinate?
Yes. A boat-tail bullet with a high ballistic coefficient retains velocity better than a flat-base bullet of the same 168-grain weight. Better velocity retention flattens the trajectory curve, lowering the maximum ordinate height at intermediate ranges.
How does changing my zero distance affect the peak height?
Switching from a 100-yard zero to a 200-yard zero forces the barrel to angle upward more steeply. This increases your maximum ordinate height, pushing the apex higher above your line of sight before it drops back down to meet the target at 200 yards.
Can I use maximum ordinate to calculate obstacle clearance?
Absolutely. If you know your maximum ordinate is 2.2 inches at 110 yards, you know the bullet will clear any obstacle sitting below that threshold within that distance window, provided your rifle is stable and level.
Why do 168-grain bullets behave differently past 400 yards?
At around 400 to 500 yards, standard 168-grain .308 bullets often transition from supersonic to transonic speeds. This aerodynamic drag transition causes unpredictable destabilization, sharply increasing drop rates that far exceed the predictable curves of early flight paths. Learn more about drag mechanics at Hornady Ballistics.
