How to mount a rifle scope

Mounting a scope on your rifle might seem like an overwhelming task, requiring a trip to the local gunsmith. But the truth is, with the right approach and a little patience, it's something any shooter can do at home. You don't need expensive specialized 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 fits your body type and shooting position precisely, and that the scope is securely mounted. 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 will go through the process step-by-step.

The right tools are half the job

Before we begin, we need to get the tools in place. Using a butter knife as a screwdriver or tightening "by feel" are the quickest ways to stripped screws and an inaccurate shot.

1. Torque wrench: This is the most important tool you will use. Overtightening is by far the most common mistake in scope mounting, and it can crush the scope tube or damage the internal mechanics. You need a torque wrench that can be precisely set in the 1.5–5.0 Nm range.
2. Spirit level: Optional, but useful. If you primarily shoot under 200 meters, you'll be fine without it. If you shoot at longer distances or in hilly terrain, a spirit level is a good investment. More on this in Step 4.
3. A stable table: 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 steady while you work.
4. Matching bits: Make sure you have the precise Allen wrenches or Torx bits that fit the screws on your mounts. A poor fit will quickly result in stripped screw heads.

What about "lapping" (grinding rings)?

Previously, it was common practice to "lap" (grind the inside of) the scope rings to ensure they aligned perfectly. With modern quality rings, this is no longer necessary. On the contrary, several manufacturers advise against it, as today's rings are CNC-milled with such fine tolerances that grinding merely removes material unnecessarily. If you buy quality rings, you can safely skip this step.

Step 1: Preparation and mounting of 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 off the contact surfaces. You may want to 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 recommend a small amount of weak threadlocker between the rail and the receiver, primarily as rust protection, while others 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.

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

Step 2: Mounting the lower ring halves

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 fit best in relation to the scope's length and your eye relief.

Tighten the rings securely 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 instructions under each product on this page!

Step 3: Adjusting eye relief

Place the scope in the lower ring halves. Attach 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 edge.

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. Carefully 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 doorframe 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, it makes a difference.

With a spirit level:

1. Place a spirit level on the Picatinny rail. Adjust the rifle until the bubble is in the middle.
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 doorframe, 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 more than good enough for most hunting distances.

Step 5: Tightening the ring screws

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

1. Find the correct torque. 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 crisscross pattern (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 it slightly, correct it, and start over.
5. Stop when the torque wrench clicks. "Just an extra turn 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 few times. Does it feel natural? Is the field of view perfect?
If so, you now have a correctly mounted scope.

The 5 most common mistakes in scope mounting

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 selection.