0 VS 20 MOA Explained – For Precision Shooting

In this guide, we’ll break down the differences between 0 MOA and 20 MOA base mounts for precision rifles. You'll learn what they are, how they work, and when each option is most suitable.

One of the key decisions long-range shooters face when setting up their rifle and scope configuration is whether to use a 0 MOA or 20 MOA base. Each has its advantages, and choosing the right one depends on your shooting needs and intended distances.

In this article, we'll explore:

• What a 20 MOA base and rail are
• The effective shooting distances for each setup
• MOA elevation travel considerations
• Using a 20 MOA base for 1,000-yard shots
• How to properly zero your rifle with different base mounts

By the end, you'll have a clear understanding of which mount best suits your long-range shooting setup.

0 & 20 MOA Explained

One of the most exciting aspects of modern target shooting and hunting is the sheer variety of equipment modifications and customization options available. With advancements in optics and firearm technology, long-distance shooting is no longer limited to 200 or 300 yards—today, shooters are consistently engaging targets at 600 to 900 yards and beyond.

To achieve precision at these extended distances, understanding MOA (Minutes of Angle) and how it applies to scope mounts and rails is essential. The right setup can maximize your scope’s elevation adjustment while ensuring you can still zero your rifle effectively.

Key Rule of Thumb for MOA Base Selection:

When choosing a base, keep the MOA of your mount less than half of your scope’s total elevation adjustment range. If your base exceeds this threshold, you may struggle to zero at closer distances, limiting your rifle's versatility.

By selecting the appropriate MOA base, you can optimize your long-range precision while maintaining practical usability across various shooting distances.

What is MOA?

In practical shooting terms, MOA (Minutes of Angle) refers to the tilt of a scope base in relation to the bore axis. This tilt determines how much elevation adjustment is available when sighting in a rifle for different distances.

A 0 MOA base has been the standard configuration for decades. It provides a flat alignment between the scope and the bore axis, meaning the line of sight and the bullet’s trajectory converge at the target when zeroed at 100 yards.

How a 0 MOA Base Affects Scope Adjustment:

• With a 0 MOA base, the scope's internal elevation adjustment range is split equally between upward and downward adjustments.
• This limits how much the shooter can dial up for long-range shots before running out of adjustment.
• For most standard cartridges, a 0 MOA base reaches its practical limits around 600 yards, after which additional elevation adjustment is often required for accurate targeting.

For shooters looking to engage targets beyond 600 yards, a 20 MOA base may provide a more effective solution, allowing for greater elevation adjustment and extended range capabilities.

Understanding a 20 MOA Base and Its Advantage

A 20 MOA base introduces a slight downward tilt to the scope in relation to the rifle’s bore axis. This setup effectively shifts the scope’s line of sight downward, forcing the shooter to dial the reticle up to align with the target.

How Does a 20 MOA Base Work?

• With a 20 MOA base, if the rifle is zeroed at 100 yards, the barrel’s natural line of fire will be 20 inches higher than the scope’s line of sight.
• To compensate, the shooter dials the scope down, aligning the reticle with the point of impact.
• This effectively shifts more of the scope’s elevation adjustment range toward long-range shooting.

What This Means for the Shooter

By using a 20 MOA base, shooters gain an additional 20 inches of elevation adjustment, allowing them to extend their effective range beyond 600 yards—often reaching 1,000 yards or more without running out of scope adjustment.

For precision shooters and long-range hunters, a 20 MOA base is an essential upgrade when targeting distances where a 0 MOA base would hit its limits.

Related Content: How To Adjust MOA With Precise Calculation

What Does A 20 MOA Scope Base Do?

Most rifle scopes have a limited elevation adjustment range, often around 40 MOA total—meaning only half of that range (20 MOA) is usable in each direction (upward and downward). This becomes a limiting factor when shooting at long distances, as standard scopes tend to run out of elevation adjustment beyond 600 yards.

The Problem with a 0 MOA Base

• When a rifle is zeroed with a 0 MOA base, the scope’s internal adjustment range is split evenly, with half available for dialing up and half for dialing down.
• The lower half of the scope’s adjustment often goes unused since long-range shooting requires elevating the reticle to compensate for bullet drop.

How a 20 MOA Base Fixes This

• A 20 MOA base reclaims the 20 MOA of wasted elevation, shifting the entire usable range upward, making more adjustment available for long-range shots.
• While the setup may feel counterintuitive at first—since the scope appears to be tilted downward—it effectively allows shooters to dial their reticle higher, extending their effective shooting range to 1,000 yards or more.

By using a 20 MOA base, long-range shooters maximize their scope’s potential, ensuring they don’t run out of adjustment when engaging distant targets.

How a 20 MOA Base Works in Practical Terms

A 20 MOA base is designed with a slight forward tilt, angling the front of the scope downward toward the rifle barrel. This adjustment increases the amount of usable elevation adjustment in the scope, making it essential for long-range shooting.

Visualizing the 20 MOA Effect

• When mounted, the rifle barrel’s line of fire is still aimed at the target’s center.
• However, the scope’s line of sight is initially 20 inches higher than the target center at 100 yards due to the base’s tilt.
• To compensate, the shooter dials the scope downward, aligning the reticle with the target.

Why This Matters for Long-Range Shooting

• This shift frees up 20 MOA of additional elevation adjustment, allowing shooters to engage targets at extended distances without running out of scope travel.
• With a 0 MOA base, most scopes max out around 600 yards. With a 20 MOA base, shooters can push out to 1,000 yards or more, depending on their rifle and cartridge.

While a 20 MOA base may feel unusual at first, as it visually appears to tilt the scope downward, it is an essential tool for precision shooting at longer ranges.

At What Range Is A 20 MOA Scope Base Needed?

Is a 20 MOA Base Always Necessary?

The decision to use a 20 MOA base depends entirely on the shooter, rifle, scope, and cartridge. While long-range shooting typically starts at 600 yards and beyond, and 1,000 yards is a common goal, a 20 MOA base is not always required for extreme distances.

When a 20 MOA Base May Not Be Needed

• Ballistic Compensating Reticle (BDS): If a scope features a BDS reticle, elevation adjustments are made using holdover marks rather than turret adjustments. In this case, a 20 MOA base provides no added benefit.
• Flat-Shooting Cartridges & Scope Limitations: Some scopes, when paired with high-velocity, flat-shooting cartridges, may not allow proper zeroing at 100 yards with a 20 MOA base. Instead, the rifle may need to be zeroed at 200 or 300 yards, which may not be ideal for all shooters.

Key Consideration Before Buying a 20 MOA Base

Before committing to a 20 MOA base, it's critical to check the scope’s total elevation adjustment range. If the scope lacks sufficient elevation travel, adding a 20 MOA base may restrict close-range zeroing and force compromises in setup.

For shooters who need flexibility across various distances, a 0 MOA base might be a more practical option. However, for dedicated long-range precision shooting, a 20 MOA base can unlock the full potential of a scope’s adjustment range.

MOA Elevation Travel

How a Scope’s Elevation Adjustment Works

When a shooter adjusts the elevation turret, the erector assembly inside the scope moves up or down within the tube. The reticle itself is suspended inside this assembly, and its movement determines the point of aim.

Understanding MOA Limits in a Scope

• Scopes typically have an internal elevation adjustment range, often 60 MOA or 100 MOA total.
• When zeroed at 100 yards, the adjustment is ideally set at half of the total range (e.g., a 60 MOA scope will have 30 MOA of upward adjustment remaining).
• This built-in limit restricts how far the shooter can dial up for long-range shots.

How a 20 MOA Base Overcomes Elevation Limits

A 20 MOA canted base tilts the scope forward, effectively shifting the zero point higher within the scope’s adjustment range. This means:

• More elevation adjustment is now available for long-range shots.
• The shooter can extend their maximum effective range without running out of turret adjustment.

Alternative to a Canted Base – COLD SHOT LLC ELR System

For extreme long-range (ELR) shooting, COLD SHOT LLC offers an innovative solution:

• A 300 MOA adjustable scope base system that eliminates the light distortion caused by bending images through multiple scope lenses.
• Instead of relying on internal scope adjustments, this system provides precise external elevation control, making it a valuable tool for extreme-range shooting applications.

For shooters looking to push the limits beyond traditional scope adjustments, solutions like adjustable scope bases can provide a significant advantage.

Learn more here

For short to medium-range shooting, a 0 MOA (flat) rail is sufficient, as most scopes provide enough internal elevation adjustment. However, at 1,000 yards, a flat base often lacks the necessary elevation travel to align the point of aim with the point of impact.

Why a 20 MOA Rail is Beneficial for 1,000-Yard Shots

• Optical Centering Matters
  Before purchasing a scope, it should be optically centered—meaning it has an equal amount of upward and downward elevation adjustment available. This ensures the shooter can fully utilize the scope’s range.
• Elevation Adjustment on a Flat Base
  A scope with 70 MOA total elevation travel will typically have around 33 MOA of usable upward adjustment when zeroed at 100 yards on a 0 MOA rail.
• Ballistics Depend on the Load
  Assuming a .308 Winchester round at 2,650 fps, a 1,000-yard shot requires approximately 36-38 MOA of elevation adjustment under optimal conditions (1,000 feet of elevation, 50% humidity, 75°F).
  • If your scope only has 33 MOA of usable elevation, you’ll fall short of the needed adjustment.
  • A 20 MOA base shifts the available elevation range, allowing for an extra 20 MOA of upward travel, ensuring you don’t max out your scope’s elevation before reaching 1,000 yards.

When a 20 MOA Base is Necessary

• If your bullet drop at 1,000 yards exceeds your scope’s usable elevation range, a 20 MOA rail is required.
• If your scope has ample internal elevation (e.g., 100+ MOA), you may not need a canted base.
• Optical clarity degrades at extreme distances, so using a 20 MOA base helps keep the erector assembly closer to the center of the scope’s optical range, improving clarity and reticle performance.

Related Content: Best Long Range Precision Scopes Under $1000

20 MOA Base and Zero

Most shooters are familiar with targeting in the 200 to the 300-yard range and zeroing their rifles at 100 yards. However, with modern ballistics, high powered scopes, and rifles, marksman want the thrill of that long-range shot. Whether this thrill equates to hunting is a whole other story.

50 Yard Laser Bore Sight

The quickest way to zero a rifle with a 20 MOA base is to use a laser bore sight first. This step gets you on paper.

Even without a laser, shooters can look through the barrel at a 50-yard target, then adjust the reticle to be at center. This will get you close, and you can make elevation adjustments from there.

100 Yard Zero

A 20 MOA rail changes the interaction between a scope's line of sight and the line of sight for the bore. The angle is widened between the two. However, the line of sight for the scope and bore remains a constant when the aiming point is specified at 100 yards.

On our site you can check out: “How To Zero A Deer Rifle“. It gives the shooter a basic awareness of the factors required in a proper Zero for. BadAss Optic takes the shooter, with any level of skill, through every detail of a Zero at 100 yards.

The 20 MOA rail raises the angle of the bore upwards, causing the bullet travel to arc higher in relation to the scope's line of sight. The result is a higher point of impact at 100 yards. The shooter must adjust elevation down to reach zero.

When the shooter backs off to longer distances, the additional elevation is now available for more up correction.

Ring height and Rifle scope Cant

Sharpshooters recommend placing the objective lens of your rifle scope as tight to the rifle barrel as possible.

The reason for this, the flight track of your bullet will be as close to the crosshairs as possible. This basic configuration eliminates or minimizes holdover/holdunder.

If you have questions about scope ring height, use this excellent Scope Ring Height Calculator to find what the optimum clearances should be. Add your objective lens size and your type of scope ring, and Mil-Rad calculates the ideal height.

Achieving proper scope alignment with your eye is essential for comfort and accuracy. In some cases, higher mounts or rings are necessary to ensure the scope’s centerline aligns with your eye position.

Common Reasons for Using Higher Mounts or Rings

1. Rifle Stock and Cheekpiece Height

   • Some rifles feature a high cheekpiece, which can make it difficult to position your eye correctly behind the scope.
   • Raising the scope using taller rings or an adjustable mount can improve ergonomics and sight picture clarity.

2. Scope Clearance Over the Barrel

   • The objective lens or the scope tube might interfere with the rifle barrel, handguard, or Picatinny rail.
   • Higher mounts provide adequate clearance between the scope and the barrel, preventing contact and maintaining proper function.

3. Eye Relief & Head Positioning

   • The ideal head position should allow a clear and full sight picture without strain.
   • A scope that sits too low can cause discomfort, requiring adjustments to head positioning or scope height.

4. Suppressor or Bolt Clearance

   • If using a suppressor or a rifle with a large bolt handle, higher rings may be needed to prevent interference when cycling the action.

Choosing the Right Scope Height

• Low mounts work best for small objective lenses and rifles with a low cheekpiece.
• Medium mounts are a good balance for most hunting and precision rifles.
• High mounts may be necessary for larger objective lenses (50mm+), AR-style rifles, or rifles with high cheekpieces.

Scope builders use different materials that are thicker, so the objective lens diameter may be closer than the shooter wants. Another issue, opening the bolt on a bolt-action rifle can interfere with the ocular lens of the scope.

Adjustable scope mounts and rings provide clearance or tightness to sidestep a lot of scope mounting troubles.

Check Out: Best 34mm Scope Rings or Best 30mm Scope Rings

Drawbacks and Problems With A 20 MOA Base

• • With a few lower quality scopes, shooters experience added parallax

• • A 20 ⦁ MOA base puts the eye piece fairly high, so there may be some comfort issues shooting from the prone position.

• • Make certain the scope does not have too much forward cant for the position you wish to shoot.

• • Some scope builders report too much negative adjustment with a 20 MOA base.

• • A few shooters have said, they are ⦁ running out of MOA elevation adjustment

Conclusion

Nothing matches the thrill of landing a 1,000-yard shot, and modern technology has pushed shooting distances beyond what most marksmen could achieve naturally. Extreme long-range shooting (ELR) is growing worldwide, with ranges now exceeding 1,500 yards—and hitting 2,500 yards is an unforgettable experience.

Rifles are evolving with 32-inch barrels, calibers surpassing .375 CheyTac, and ammunition costing $8 per round. A well-built long-range setup can easily exceed $5,000.

The 20 MOA base has become a standard in hunting and precision shooting, with many opting for it regardless of necessity. As technology advances, so will the shooters pushing the limits of extreme distance shooting.