Rifle Scope Mounts and Rings: A Guide
You ordered a new rifle scope, the box arrived, and now you're staring at a pile of rings, bases, and a torque wrench wondering where to begin. It happens to most shooters the first time. Choosing the right mount or rings comes down to four variables: tube diameter, ring height, base type, and whether you need a canted rail for extended-range correction — get those four right and everything else is mechanical execution.
Key takeaways
- The Accufire EVRO-12 and ATRO-20 both use 30 mm tubes — buy 30 mm rings, not 1-inch.
- Ring height determines whether the objective lens clears the barrel and whether you get a consistent cheek weld; medium rings fit most setups, but measure before ordering.
- A 20-MOA canted base or integrated cant in a one-piece mount adds roughly 20 inches of additional elevation travel at 100 yards, useful for long-range holds beyond 500 yards.
- One-piece mounts are faster to install and more rigid; two-piece rings offer more flexibility across different receiver lengths and are often less expensive.
- Torque every fastener to the mount and scope manufacturer's specification — over-torquing crushes scope tubes; under-torquing lets rings shift under recoil.
Tube diameter: the one number that cannot be wrong
Rings are sized to match a scope's main tube, and confusing this measurement means your scope either won't seat or will be crushed. Both Accufire rifle scopes — the EVRO-12 and the ATRO-20 — use a 30 mm main tube. That is the body of the scope between the objective bell and the eyepiece, not the bell itself (which is 50 mm on both models). When you order rings or a one-piece mount, the spec that matters is the ring bore diameter: 30 mm. Do not order 1-inch (25.4 mm) rings by mistake — they are the most common sizing error and the rings simply will not close flush around the tube.
If you own a different scope with a 34 mm or 35 mm tube, those rings are not interchangeable with a 30 mm scope. Check the manufacturer's spec sheet, not the bell size.
Ring height: clearing the barrel and finding your cheek weld
Ring height is measured from the top of the rail to the center of the bore axis. It determines two things: whether the objective bell physically clears the barrel contour, and how high your head must rise off the stock to get a full sight picture. Lower rings bring your eye closer to the stock — ideal for a natural cheek weld on a flat-top AR or Picatinny-equipped rifle. Higher rings become necessary when a large objective lens would otherwise contact the barrel or when a heavy contour barrel fills the channel.
For the EVRO-12 (44 mm objective) and the ATRO-20 (50 mm objective), both on 30 mm tubes, medium-height 30 mm rings (roughly 0.86"–1.0" center height) will clear most standard barrel profiles on a flat-top AR or bolt gun with a standard rail. Measure the clearance at the objective bell before ordering — you want at least 3–4 mm of air between the bell and the barrel surface. Extra high rings work when you have a heavy bull barrel or a raised rail, but they force your head up and can compromise cheek weld consistency, which hurts shot-to-shot repeatability at longer range.
One-piece mount vs two-piece rings: practical differences
Both approaches hold a scope reliably when installed correctly. The differences are practical rather than performance-defining at most shooting distances.
| Feature | One-Piece Mount | Two-Piece Rings |
|---|---|---|
| Installation speed | Faster — single unit, one rail clamp | Slower — each ring aligned independently |
| Rigidity | Higher — single rigid chassis | Slightly less; depends on rail interface and ring quality |
| Rail length required | More — mounts span 3–4 slots minimum | Less — rings can fit on shorter or interrupted rails |
| Cant integration | Often built-in (0 MOA or 20 MOA options) | Cant goes in the base; rings are typically neutral |
| Cost | Generally higher for equivalent quality | Often less expensive at entry/mid level |
| Return-to-zero after removal | Very consistent on quality Picatinny mounts | Good on lapped, torqued rings; requires re-check |
A quality one-piece mount from manufacturers like Vortex, Nightforce, or Leupold will index repeatably on a Picatinny rail every time you remove and reinstall it. Two-piece rings in equivalent quality steel or aluminum work just as well for rifles that stay assembled; they become the practical choice when your receiver has an interrupted rail or non-standard spacing between the front and rear mounting positions.
The 20-MOA canted base: when and why
A flat (0 MOA) mount places the scope's optical axis parallel to the bore axis. That's fine for targets out to roughly 300–400 yards with most centerfire cartridges, because the scope's internal elevation adjustment has enough range to compensate for bullet drop. Push beyond that distance and some combinations of cartridge, scope, and mount run out of upward elevation travel before they get enough correction dialed in.
A 20-MOA canted base or one-piece mount pre-tilts the scope slightly downward relative to the bore. At 100 yards, 20 MOA equals roughly 20 inches of additional elevation headroom. In practical terms, you zero at 100 yards while the scope is already partway through its elevation range, leaving more internal travel available for long-range holdovers. This matters most for cartridges with significant drop at distance — .308 Win, 6.5 Creedmoor, .300 Win Mag — and for the EVRO-12's 3–12× and ATRO-20's 2.5–20× ranges, where you'll likely be dialing to real distances rather than just holding over. If you shoot primarily under 300 yards, a flat base is simpler and works well. If you're stretching to 600 yards and beyond, a 20-MOA base is worth the minor additional cost.
For more on how turret travel relates to range work, the MOA vs MRAD guide covers the math behind click values and how they translate to real-world adjustments.
Leveling, lapping, and torque: the steps most shooters skip
A misaligned scope creates cant error — your point of impact drifts left or right as you dial elevation, not just up or down. Use a two-bubble level system (one on the rail, one on the scope turret) or a scope-leveling kit to ensure the reticle's vertical crosshair is truly plumb with gravity before tightening the rings. This matters most on scopes with a mil or MOA reticle used for elevation holds, including both the EVRO-12 and ATRO-20.
Lapping is the process of running an abrasive lap rod through both rings simultaneously to ensure their bores are in perfect axial alignment. It eliminates stress on the scope tube that can occur when ring bores are slightly misaligned. Lapping is most valuable on two-piece rings where independent alignment is harder to guarantee, and on precision rifle builds where you're torquing to higher values. On quality one-piece mounts machined to tighter tolerances, lapping is often unnecessary but still not harmful.
Torque values are the step that causes the most damage when skipped or guessed. The general guidance from most precision mount manufacturers is 15–18 in-lbs for ring cap screws on aluminum rings and 25–30 in-lbs for steel rings, but these ranges vary by product — always follow the specific numbers in the mount manufacturer's instruction sheet. For the scope body, ring cap screws should be tightened in a cross pattern (like lug nuts) to distribute clamping force evenly. Do not guess. Do not use a standard hex key with feel alone. A quality torque wrench set to the manufacturer's value takes 30 seconds and removes all ambiguity. Over-torquing aluminum ring caps strips threads or permanently dents the scope tube; under-torquing lets the scope walk under recoil, shifting your zero.
After torquing, perform a bore-sight check and confirm zero at the range before relying on the setup. Understanding how to zero a rifle scope properly will confirm your mount is holding and your adjustments are tracking correctly.
An honest limitation: Accufire makes scopes, not mounts
Accufire builds the EVRO-12 and ATRO-20 rifle scopes — it does not currently manufacture rings or mounting hardware. That means you'll source your rings and base separately from makers like Vortex, Leupold, Nightforce, Seekins Precision, or similar. The specs you need from this guide (30 mm tube, your preferred ring height, flat or 20-MOA cant) let you filter those options accurately. The scope is where Accufire's R&D sits: first focal plane reticles, 0.1 mrad clicks, locking turrets on the EVRO-12, and a 3–12× range on the EVRO-12 and a 2.5–20× range on the ATRO-20, working from close-range hunting to extended precision shooting.
Ready to mount a capable FFP scope? The EVRO-12 and ATRO-20 both use 30 mm tubes — pair them with the rings and base you've selected, torque to spec, and get to the range — shop Accufire rifle scopes.
Accufire EVRO-12 — $479.00, first focal plane 3–12×44 with 30 mm tube, 0.1 mrad clicks, mil reticle, and locking turrets. A strong value option for mid- to long-range work. View the EVRO-12.
Frequently asked questions
What ring size do I need for the Accufire EVRO-12 or ATRO-20?
Both the EVRO-12 and ATRO-20 have 30 mm main tubes, so you need 30 mm rings. The EVRO-12's objective bell is 44 mm and the ATRO-20's is 50 mm, but ring diameter is measured at the main tube, not the bell.
Do I need a 20-MOA canted base for the Accufire EVRO-12?
It depends on your shooting distance. A 20-MOA cant adds roughly 20 inches of additional elevation travel at 100 yards, which is useful for shooting beyond 500 yards. For ranges under 400 yards, a flat 0-MOA base is typically sufficient and simpler to set up.
Should I use a one-piece mount or two-piece rings?
One-piece mounts are faster to install, more rigid, and often include an integrated cant option. Two-piece rings work better on receivers with shorter or interrupted rails and tend to cost less at the entry and mid tier. Both hold zero reliably when torqued correctly and aligned properly.
What torque should I use on rifle scope rings?
Always torque to the ring manufacturer's specification printed in the instruction sheet, not a general rule. Most aluminum ring caps call for 15 to 18 in-lbs and most steel ring caps call for 25 to 30 in-lbs, but the exact number varies by product. Use a calibrated torque driver and tighten in a cross pattern to distribute clamping force evenly.
Do I need to lap my rifle scope rings?
Lapping is most beneficial on two-piece rings where the two bores can sit slightly out of alignment, and on precision rifle builds where even stress on the scope tube matters. Quality one-piece mounts machined to tight tolerances generally do not require lapping, though it does not hurt. If you see witness marks on the scope tube after removing the rings, the bores were not aligned and lapping would have helped.
Mounting hardware is the foundation that lets a scope perform to its designed accuracy. For a deeper look at how scope optics work once you have them mounted, the rifle scopes complete guide covers parallax, eye relief, focal planes, and reticle choices — all the variables that determine how the EVRO-12 and ATRO-20 perform once they're correctly seated in your rings. If you're also building an understanding of click values and turret adjustments, the first focal plane vs second focal plane comparison explains why FFP reticles like those in the Accufire lineup stay accurate at every magnification setting.