Two angular measurement systems for scope adjustments. Neither is "better"—choose based on your community and training.
MOA (Minute of Angle)
1 MOA = 1.047" at 100 yards
≈ 1 inch at 100 yards (practical)
US hunting standard
Intuitive at 100 yards
Common clicks: ¼ MOA, ⅛ MOA
Mils (Milliradians)
1 mil = 3.6" at 100 yards
1 mil = 10 cm at 100 meters
Military/PRS standard
Clean metric math
Common clicks: 0.1 mil
Conversion: 1 mil = 3.438 MOA | 1 MOA = 0.291 mil
The Real Golden Rule:
You can't change your scope's reticle or turrets—know what you have.
The key is understanding the linear value per click at any distance:
Linear value = (angular value) × (distance / reference)
¼ MOA click @ 400yd = 0.25 × (400/100) × 1.047" = 1.047"
0.1 mil click @ 400m = 0.1 × (400/100) × 10cm = 4 cm
This formula makes your scope a measurement tool and rangefinder—not just crosshairs.
Fun Fact: USMC Mil-Dot with MOA Turrets
The USMC's Unertl 10× (and later the Schmidt & Bender 3-12×50) paired a mil reticle
with MOA turrets. Why? The mil-dot reticle excels at range estimation
(target size in mils → distance), while MOA turrets provided finer click adjustments
(¼ MOA ≈ 0.07 mil). Marines learned both systems—ranging in mils, dialing in MOA.
Source: USMC Scout Sniper Training Manual, FM 23-10
Choosing Your Zero Distance
Zero distance is one of the most debated topics in shooting. There's no single "right" answer—
the best zero depends on your intended use, typical engagement distances, and caliber.
KNOMAD gives you the tools to test any zero and see the data.
36 yd
Improved Battle Zero
Popular for AR-15/M4 carbines. Bullet crosses sight line at ~36 yards (going up),
peaks around 200 yards, crosses again at ~300 yards (coming down).
Pros: Point-and-shoot 0-300yd with ~2" max deviation. USMC standard for M4.
Cons: Requires understanding trajectory arc. Not intuitive for precision.
50 yd
Close Engagement Zero
Optimized for close-range work. Bullet is nearly flat from muzzle to 150 yards
for most rifle calibers. Popular for brush hunting and home defense.
Pros: Simple at close range. Good for dense terrain under 150yd.
Cons: Significant drop at extended ranges. Requires holdover past 200yd.
100 yd
Classic Standard
The most common zero worldwide. Provides a known baseline for calculating
drop at any distance. Standard for most hunting rifles and precision shooting.
Pros: Universal reference. Easy math. Most ballistic data uses 100yd baseline.
Cons: Some holdover needed at 200+ yards depending on caliber.
200 yd
Extended Range Zero
Popular among western hunters and tactical shooters. Bullet is only ~2" high
at 100 yards (caliber dependent), drops are reduced at 300-400 yards.
Pros: Flatter trajectory at common hunting distances. Less holdover at 200-400yd.
Cons: Must know your 100yd offset. Not ideal for precision at short range.
300 yd
Long Range Precision
Used by some long-range precision shooters and PRS competitors.
Optimized for engagements at 300-600+ yards where most shots occur.
Pros: Minimizes adjustment at primary engagement distances. Common in competition 300+.
Cons: Significant holdunder at close range. Requires precise trajectory knowledge.
The MPBR Concept (Maximum Point-Blank Range):
Some shooters choose their zero based on MPBR—the distance at which you can aim center-mass
and hit a target of a given size without holdover. For a 6" vital zone, a .308 Win might
have an MPBR of ~275 yards with a ~225 yard zero. KNOMAD's PyBal calculator can compute
your specific MPBR based on your load data.
Sources: Bryan Litz, Applied Ballistics for Long Range Shooting;
USMC TM 09244A-23&P/2 (36-yard battle zero); NRA Rifle Marksmanship Guide.
Precision Statistics
ES — Extreme Spread: max distance between any two shots
MR — Mean Radius: average distance from center
σ — Standard deviation (ES / multiplier)
CEP — 50% containment radius ≈ 1.18σ
R95 — 95% containment radius ≈ 2.45σ
Zero Conditions & Environmental Factors
When to use this correction:
If you're shooting under the same conditions (temperature, altitude, humidity) as when you last zeroed, the MPI offset represents a true zero error that can be corrected.
When to re-zero instead:
If environmental conditions have changed significantly, your point of impact shift may be atmospheric, not mechanical. Applying a scope adjustment could compound the error when conditions change again.
Best Practice (Bryan Litz, Applied Ballistics):
"A rifle zeroed at sea level on a 59°F day will shoot approximately 0.5 MOA high at 5,000 feet elevation on an 80°F day at 500 yards. This is not a zero error—it's atmospheric. Adjusting your scope for this shift means you'll be off when you return to original conditions."
Rule of thumb:
Same conditions: Apply correction to scope
Different conditions: Use ballistic calculator for atmospherics
Group size only: Correction is informational only
Complete Ballistics Table
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Click "Calculate & Import to KNOMAD" first to generate ballistics data.