Optics · How-To
How to mount and level a scope: rings, height and cant
Researched by James · Updated September 26, 2026 · Editorial policy
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Mounting steps and torque specifications below come from optics and mount manufacturer guidance, cited at the bottom of this page. Full methodology & editorial policy →
A scope that won't hold zero or strings shots sideways at distance is a mounting problem more often than people assume. Here's the process in the order that actually prevents both.
Where should scope rings sit on the tube?
Position the rear ring no closer than about 3/8 inch from the magnification adjustment ring, and the front ring centered or slightly forward on the tube, then fine-tune both for eye relief once the rifle is shouldered. Pick the lowest ring height that clears the objective bell over the barrel or, on a bolt gun, still lets the bolt handle cycle without hitting the ocular housing.
How do you get eye relief right?
Shoulder the rifle naturally at the scope's highest magnification, since eye relief gets less forgiving at high power, and slide the scope forward or back in the rings until you get a full sight picture with no dark shadowing around the edges, with your head in a normal, repeatable cheek-weld position. Most hunting scopes specify 3-4 inches of eye relief; get close to the middle of that range so small position changes in the field don't black out your view.
How do you actually level a scope?
- Secure the rifle in a vise or on sandbags so it can't rotate while you work.
- Level the rifle itself using a bubble level on a flat part of the receiver or picatinny rail.
- Level the scope by removing one turret cap and setting a small bubble level directly on the flat top of the turret's adjustment screw, which reads the scope's internal reference more accurately than the tube's outer housing.
- Or use a plumb line as a lower-cost method: hang a weighted string a few feet in front of the muzzle and rotate the scope in the rings until the reticle's vertical line matches it exactly.
- Snug the rings evenly by hand first, re-check level, then move to final torque.
Skipping this step is the single most common reason a scope that groups fine at 25 yards starts stringing shots left or right once you dial elevation for a longer holdover; see building a real holdover chart for why a canted reticle ruins that math specifically.
What torque should you use?
| Fastener | Typical torque | Source / notes |
|---|---|---|
| Ring screws (to scope tube) | ~15-25 in-lb | Warne: "20-25 in-lb used to be the standard," now varies by scope; hand-tight lands around 15-20 in-lb |
| Ring-to-base screws | ~15-18 in-lb | Vortex mounting guide |
| Base-to-receiver (steel) | ~25 in-lb max | Warne general guidance |
| Base-to-receiver (aluminum) | ~15 in-lb | Warne general guidance |
| Base-to-rail (some mount systems) | 35-45 in-lb | Vortex mounting guide, for its own base hardware |
These are starting points, not universal law: always check the specific torque spec printed by your rifle, base, or ring manufacturer before you commit to a number, since receiver material and mount design both change what's safe. Use dry, clean threads on ring screws rather than thread locker, since locker changes friction and throws off a specified torque reading. Tighten horizontally-split rings evenly on both sides; on vertically-split rings, fully seat one side before the other.
Does mounting change for spring-piston (springer) airguns?
The steps are identical, but the hardware requirement changes. Springers recoil in both directions, forward when the piston slams shut and backward as it recoils, which loosens or damages scopes and rings that were only built and tested for one-way PCP or firearm recoil. Look for a scope and ring set explicitly rated for spring-piston use, like Leapers/UTG's True Strength platform, and re-check torque after the first few dozen shots since springer vibration works screws loose faster than a PCP's smoother recoil impulse.
What if the scope still won't hold zero after mounting correctly?
Re-check torque after the first outing, since new hardware and fresh recoil often seat slightly. If it still walks, the scope itself may be out of adjustment range or damaged internally, which is a different problem than mounting; our troubleshooting guide for inconsistent PCP shooting covers the rifle-side causes that get mistaken for a bad scope. If you're adding a scope cam alongside the optic itself, mounting order and rail space both matter; see how to film hunts through your scope.
FAQ
How high should scope rings be?
Pick the lowest ring height that still clears the objective bell over the barrel and, on a bolt gun, lets the bolt handle cycle freely. Rings that sit too high raise your cheek off the stock, which hurts your natural point of aim and consistency shot to shot.
Do I need a torque wrench to mount a scope?
You don't strictly need one, but it removes guesswork. Hand-tightening typically lands around 15-20 in-lb, which is in range for most ring screws, but base screws and different manufacturers' rings can call for anywhere from 15 to 45 in-lb, and a cheap inch-pound torque driver removes the risk of stripping threads or leaving a scope loose enough to shift zero.
How do I level a scope without an expensive level kit?
Rest the rifle in a vise or on sandbags so it can't rotate, set a small bubble level on a flat part of the receiver rail to confirm the rifle itself is level, then remove one turret cap and set the level directly on the flat top of the turret's adjustment screw to check the scope. A plumb line hung a few feet away, aligned with the reticle's vertical crosshair, works as a low-cost alternative.
What happens if a scope is mounted canted (not level)?
A canted scope makes elevation adjustments bleed sideways: dial up for a longer shot and the group also drifts left or right, growing worse the further you shoot. It's one of the most common causes of a rifle that seems to shoot fine up close but strings shots at distance.
Should you use thread locker on scope ring screws?
No, most manufacturers specify dry, clean threads for ring screws so torque values are accurate and repeatable; thread locker changes the friction and can throw off a specified torque reading. Base-to-receiver screws sometimes call for thread locker depending on the rifle and mount, so check that specific manufacturer's instructions.
What eye relief distance is correct?
It depends on the scope's specified eye relief range, typically 3-4 inches on most hunting scopes, but the practical test is this: shoulder the rifle naturally at your highest magnification and slide the scope fore-and-aft in the rings until you get a full, clear sight picture with no dark shadowing at the edges, with your head in a comfortable, repeatable position.
Do airgun and springer scopes mount differently than firearm scopes?
The mounting steps are the same, but springers add a requirement: use scope rings and a scope rated for spring-piston recoil, which pushes in both directions instead of one. A scope or ring set only tested on PCP or firearm recoil can loosen, walk zero, or crack internally on a hard-kicking springer.
How tight should base screws be?
It depends on what they're threading into. Warne's general guidance is up to roughly 25 in-lb on steel receivers and about 15 in-lb on aluminum, while some manufacturers' own base-to-rail hardware calls for 35-45 in-lb; always defer to your specific rifle or mount manufacturer's spec over a generic number.