How to mount a rifle scope

Mounting a scope on your rifle might seem like an overwhelming task that requires a trip to the local gunsmith. But the truth is, with the right approach and a little patience, it's something any shooter can handle at home. You don't need expensive special tools or years of experience – just the right method and attention to detail.

When you mount the scope yourself, you have full control over the process. You ensure that the eye relief is perfectly suited to your physique and shooting position, and that the scope is seated correctly. And should you ever change your scope, mount, or rifle, you can do it yourself without waiting for an appointment with the gunsmith.

In this guide, we'll walk you through the process step-by-step.

The right tools are half the battle

Before we begin, let's get our tools in order. Using a butter knife as a screwdriver or tightening "by feel" are the quickest ways to stripped screws and an off-target shot.

1. Torque wrench: This is the most important tool you will use. Overtightening is by far the most common mistake when mounting a scope, and it can crush the scope tube or damage the internal mechanics. You need a torque wrench that can be precisely adjusted in the 1.5–5.0 Nm range.
2. Spirit level: Optional, but useful. If you primarily shoot under 200 meters, you'll do fine without one. If you shoot at longer distances or in undulating terrain, a spirit level is a good investment. More on this in Step 4.
3. A stable workbench: You don't need an expensive "gun vise." A kitchen table or workbench works fine. Sandbags, a rolled-up jacket, or a couple of books under the stock will keep the rifle still while you work.
4. Matching bits: Make sure you have the precise hex keys or Torx bits that fit the screws on your mounts. A poor fit will quickly result in stripped screw heads.

What about "lapping" (ring alignment)?

Previously, it was common practice to "lap" (grind the inside of) scope rings to ensure perfect alignment. With modern quality rings from manufacturers like Nieload, Rusan, and Spuhr, this is no longer necessary. On the contrary, several manufacturers advise against it, as today's rings are CNC-machined with such high tolerances that grinding merely removes material unnecessarily. If you buy quality rings, you can safely skip this step.

Step 1: Preparation and mounting the base/rail

Start by ensuring the rifle is unloaded. Remove the bolt, if possible. Then, place the rifle stably on your table with sandbags or similar, so it remains still.

If you are mounting a Picatinny rail (the base), first wipe down the contact surfaces. You may apply a very thin layer of oil to the underside of the rail to protect against rust, but avoid getting oil into the screw holes.

Place the rail on the receiver. Some manufacturers (like Nieload) recommend a small amount of weak threadlocker between the rail and receiver, primarily for rust protection, while others (like HG Firearms) recommend regular gun oil and specifically advise against threadlocker. Follow the manufacturer's recommendation.

Tighten the screws to the torque specified by the manufacturer. For Picatinny rails, this is typically 3.5 Nm (which applies to both HG Firearms and Nieload).

(Note: A Picatinny rail raises the mounting point. This means you can often choose a lower scope mount than if you mounted directly to the receiver. The measurement is typically given "from bottom to ring edge").

Step 2: Mounting the lower ring half

Place the lower halves of your scope rings on the Picatinny rail. The advantage of a rail is that you have great freedom to position the rings exactly where they best suit the scope's length and your eye relief.

Fasten the rings to the rail. The torque here depends on the manufacturer, but is often around 3.5 – 4.0 Nm for a fixed mount. For Rusan rings, the torque is lower, around 1.8 – 2.0 Nm, due to their specific construction. Always read the manual!

Step 3: Adjusting Eye Relief

Place the scope loosely in the lower ring halves. Put on the upper ring halves and lightly screw in the screws – just enough so the scope doesn't fall out, but can still slide back and forth and rotate.

Now you need to find the correct eye relief. This is the distance between your eye and the scope's rear lens (eyepiece), where you have a full, clear, and sharp field of view without black shadows at the edges.

1. Set the scope to its highest magnification. Eye relief is most critical (and least forgiving) at high magnification.
2. Pick up the rifle from the table and shoulder it in your normal shooting position.
3. Close your eyes, find a comfortable cheek weld on the stock, and open your eyes.
4. Do you have a perfect field of view? If not, the scope needs to be moved forward or backward.

Repeat the process until the scope is perfectly positioned every time you shoulder the rifle. Ensure that the scope rings are at least 1 centimeter away from the scope's adjustment turrets and the rear magnification ring. Gently place the rifle back on the table.

Step 4: Leveling the scope

If you have a spirit level, this is where you use it. If not, you can use a vertical reference – a door frame or a plumb line – to assess whether the reticle (crosshairs) is level.

Why it's relevant: If the reticle is tilted relative to the rifle, your click adjustments will send the bullet slightly to the side, instead of straight up or down. At short distances (under 100-200 meters), the effect is minimal and hardly noticeable. But if you shoot at longer distances, or hunt in undulating terrain where the horizon is not a reliable reference, it makes a difference.

With a spirit level:

1. Place a spirit level on the Picatinny rail. Adjust the rifle until the bubble is centered.
2. Place the second spirit level on top of the scope's upper adjustment turret.
3. Gently rotate the scope inside the rings until both spirit levels align.

Without a spirit level:

1. Place the rifle stably and point it towards a clear vertical line (a door frame, a plumb line, the edge of a building).
2. Look through the scope and rotate it until the vertical line in the reticle aligns with the vertical reference.
3. It's not perfect, but it's good enough for most hunting distances.

Step 5: Tightening the ring screws

Now the scope needs to be securely fastened. This is where the torque wrench truly comes into its own. The most common mistake is overtightening the ring screws, which can squeeze the scope tube into an oval shape and damage the internal lenses and adjustment mechanisms.

1. Find the correct torque. For Nieload ring screws, it is 2.5 Nm. For Rusan rings, it is 1.8 – 2.0 Nm. Never use threadlocker on the ring screws, as it lubricates the threads and will cause you to overtighten, even with a torque wrench.
2. Tighten the screws in a cross pattern (just like changing a car tire). Tighten a little at a time – a quarter turn on each screw.
3. Keep an eye on the gap between the upper and lower ring halves. The gap should be even on both sides of the scope. Rings touching on one side and gapping on the other is a classic mistake.
4. Continuously check that the scope has not rotated. The scope tends to rotate slightly when the screws are tightened. If this happens, you must loosen slightly, correct, and start over.
5. Stop when the torque wrench clicks. "Just one extra click for good measure" is forbidden here.

The final check

Once everything is tightened to the correct torque, pick up the rifle and shoulder it a couple of times. Does it feel natural? Is the field of view perfect?

If so, you now have a correctly mounted scope. Proper mounting, combined with the benefits of a Picatinny rail (which allows for easy switching between different optics, including night optics with saved zero profiles), gives you the best foundation for accurate shots.

The 5 most common mistakes in scope mounting

Mistake	Consequence	Solution
Overtightening of ring screws	Scope tube squeezed into an oval shape, internal mechanisms damaged	Always use a torque wrench, follow manufacturer's specifications
Scope not level	Shots drift sideways when adjusting elevation	Use a spirit level or vertical reference
Incorrect eye relief	Poor field of view or "scope bite" (scope hitting eyebrow)	Adjust at highest magnification in normal shooting position
Incorrect tools	Stripped screw heads, imprecise tightening	Use precisely fitting bits, never "almost"
Uneven tightening	Scope twisted, rings stressing tube unevenly	Tighten in a cross pattern, a little at a time, watch the gap

Summary

Scope mounting is not rocket science. With a torque wrench, a little patience, and the right approach, you can achieve a result that is at least as good as what most gunsmiths deliver. The key is to take your time, follow the torque specifications, and ensure the scope is level before tightening it down.

Do you need a Picatinny rail for your rifle, or are you looking for the right scope rings? Read more in our knowledge center, or browse our assortment.