It’s no secret that low-power variable optics are slowly conquering the tactical rifle market. With the capabilities of modern LPVOs, they’re a solid option on any AR-15 or similar rifle, with the exception of certain special-purpose firearms like SBRs or DMRs.
LPVOs offer a level of versatility red dots and higher-powered optics just can’t match, even when taking into account accessories like magnifiers for red dots or offset and piggyback optics for traditional scopes.
At low power, they offer most of the speed of a red dot. At their high power, they offer much of the precision of a traditional scope. The only area in which they really fall short is their magnification range, historically limited to a 4x or 6x maximum power.
Modern LPVOs with 8x power settings pushed the envelope, letting marksmen with rifles chambered in intermediate calibers take advantage of their full effective range.
With the recent proliferation of 1-10x optics, the game has been changed again. Now, even battle rifles in full-power rifle cartridges can utilize a single optic at every engagement distance. With our new SLx® 1-10x28mm SFP Rifle Scope, we’re proud to offer an optic that can not only perform at any distance but fit nearly any budget as well.
10x Mag Range
Optics with 1-10x magnification ranges are a relatively recent innovation, which only entered the market in the last decade. Even now, 1-10x scopes are just becoming affordable as the technology as the technology grows more common.
Because these optics are relatively new, there’s a fair amount of misunderstanding about their role and optimal use cases. They’re not a true replacement for a red dot—especially not on a short home-defense gun or duty rifle designed for room clearing—nor are they an appropriate substitute for a traditional high-powered scope on a firearm designed solely for precision.
What they are is the latest evolution of the low-powered variable scope and arguably the most versatile general-purpose optic ever created. Firearms with specific, narrowly defined roles generally benefit from optics that are similarly tailored to the expected use case. For many of us, though, our rifles fill multiple roles. One of the greatest advantages of the AR-15 is its ability to serve in a wide range of capacities, from a hunting rifle to a home defense gun to a target and competition firearm.Shop all SLx 1-10x SFP Scopes
A 1-10x optic complements that versatility perfectly. For those who own only one or two rifles and use them in multiple roles, a 1-10x magnification range offers the broadest optical capability. An old, oft-cited rule of thumb is that an average shooter needs 1x of magnification per 100 yards of distance to effectively engage a target. Under this rule, a scope with a maximum power of 6x could be effective out to 600 yards, 8x out to 800 yards, and a scope with a maximum power of 10x could reach out all the way to the 1000-yard range often considered to be the gold standard of long-range shooting.
For an AR-15, this may sound overkill, and with good reason; common .223 and 5.56 loads out of a 16″ barrel are often ineffective beyond 600 yards, so it’s easy to call 6x “good enough” and dismiss everything greater, but this does the user a disservice. 1x of magnification per 100 yards of distance is a minimum metric, not an ideal one. In many precision applications, more magnification is better.
Greater magnification means a closer, more detailed image of the target or area being viewed. For hunting or competition, this means an easier time spotting targets, a more sophisticated view of the area around and behind them, and a more precise crosshair position. For tactical applications, a more detailed view can be vastly more beneficial.
For AR-15s chambered in non-standard rounds such as .224 Valkyrie or 6mm ARC, a 1-10x optic may be the only LPVO that offers sufficient magnification to take advantage of the cartridge’s long-range capability. This is also the case for battle rifles chambered in full-power rifle rounds, such as the SCAR 17S.
Notably, these advantages come without forfeiting the speed and capability of the 1x power setting; whether in a 1-10x or a 1-6x scope, the lowest setting is still just as fast at CQB. This is not to say that 1-10x optics have no drawbacks compared to lower magnification range LPVOs, but for many users the increased zoom is more than worth the cost.
Design Challenges
A 10x magnification range scope isn’t exactly a novel idea—there are several on the market at various price points—but we’re never satisfied with just matching the market. We don’t release a new optic unless we can improve on existing models in some way.
With a 10x magnification range scope, whether it’s 1-10x, 2-20x, etc., there are certain drawbacks inherent in the design. These scopes tend to be larger and heavier than their lower-range counterparts, and they often have punishingly tight eye boxes at their upper magnification levels.
To a certain degree, these limitations are just the price you pay for the extreme versatility of a 10x range optic. But, through clever design and engineering, each of these detriments can be minimized, creating a scope that is only slightly heavier and larger, and slightly tighter in the eye box.
This was the objective for our SLx 1-10x28mm SFP: a scope that could cover everything scenario, from across the room to across the range, without burdening the user with excessive weight or an unusably small eye box.
Since our new 1-10x is part of our SLx lineup, though, we couldn’t simply throw money at the problems. In addition to performance, we demand that our SLx scopes deliver best-in-class value as well. We wanted a 1-10x scope that not only could tackle every use case but could also fit nearly every budget.
As you can see, it was a tall order. As you’ll see below, we delivered.
SLx 1-10: Design
One of the biggest challenges in designing an optic with a 10x magnification range is the eye box, specifically the exit pupil. We won’t bore you with the physics, but it essentially boils down to this; all else being equal, the bigger the magnification range, the smaller the eye box at max power.
This makes creating a useful scope with a magnification range greater than 8x very challenging, especially in a low-power variable optic. In a target scope, a tight eye box is an annoyance, but not that much of a hindrance. After all, the target’s not going anywhere, and most target shooting is done from a bench. You’ve got plenty of time to settle into a comfortable shooting position, find the perfect head placement and cheek weld, and then take your shot.
LPVOs, though, are made for more dynamic environments. Shots often have to be taken quickly, sometimes from improvised or unorthodox shooting positions. In these situations, an overly tight eye box can be debilitating.
For this reason, we decided to increase the objective lens and tube diameter in our SLx 1-10x. Increasing the diameter of the main tube to 34mm allows for a larger 28mm objective lens, which increases the size of the exit pupil, thereby increasing the size of the eye box.
Shop all Primary Arms Optics GLx 34mm Scope Mounts
Compared to our SLx 1-6x24mm FFP scope, the 1-10x28mm has an exit pupil diameter just 1.2mm smaller at maximum magnification—but that maximum setting is now 10x instead of 6x. At the minimum magnification setting, the exit pupil diameters of the two scopes are identical.
While the eye relief on the SLx 1-10x28mm is slightly shorter, with proper scope mounting, it should be every bit as fast and easy to use at 1x as our 1-6x. The eye box won’t be as forgiving at maximum power, but if you’re taking the time to dial up to max power, you’re most likely engaging a target at a considerable range. For an 800-yard shot, you’re going to need a stable position and good cheek weld to land an effective hit anyway, minimizing any limitations the eye box imposes.
The 28mm objective lens comes with other benefits as well. A larger objective lens gathers more light, which results in a brighter picture for the user. This is why many target and long-range scopes have large objective lenses—often in the 40-50mm range—to allow for the best, brightest image possible. Image brightness is especially important if you’ll be using the optic in low-light conditions; if there isn’t much light to begin with, you’d better make sure your scope is gathering as much of it as possible.
Despite the increased magnification and larger main tube, we managed to keep the SLx 1-10x SFP lightweight. Tipping the scales at just 19.1 ounces, our 1-10x is one of the lightest scopes in its class. It’s also only 10.5″ long, so it won’t monopolize rail space on your rifle.
SLx 1-10: Features
Image quality and magnification power are huge factors in a scope’s optical performance, but when it comes to real-world capability, they’re only part of the picture. The clearest and best picture in the world can only do so much for you if you can’t effectively work your scope’s controls or if it’s not tough enough to survive your operating environment.
Luckily, we have plenty of experience designing optics for real-world use, so we made sure the SLx 1-10x has all the features you need to be effective and none of the unnecessary bloat that can slow you down.
It starts with little things like the integrated but changeable magnification throw lever. The scope comes with a fixed lever installed for fast magnification changes, even under stress or with sweaty hands. Since the SLx is intended to be your rifle’s one do-all optic, being able to switch magnification levels quickly is paramount, eliminating the need for a piggybacked or offset red dot.
The lever is mounted using a dovetail system on the magnification ring, so it’s easy to detach if you’d prefer to swap to a folding lever but also extremely durable. Unlike aftermarket friction-fit levers, it’s never going to get bumped off or slip on the magnification ring.
While the SLx 1-10x SFP does dial up to 10x, it’s not a ‘true’ precision scope. It’s certainly capable of precise shots, but it wasn’t made with tiny, one-ragged-hole groups in mind. It’s a tactical scope, and so for that reason, we opted for capped turrets to protect the user’s zero while in the field. They are still finger-adjustable, though, so if you find yourself needing to dial for range, you’ll still have that capability.
In keeping with that tactical vision for this optic, the illumination settings feature both night-vision and daylight-visible options.
Naturally, we insist that all of our optics be as tough as the guns they ride on, so the SLx 1-10x is built with a one-piece 6061-T6 aluminum main tube and hard-coat anodized for corrosion resistance. You can rest easy knowing your scope can take a beating; we’ve tested the optic extensively in live-fire exercises with a SCAR 17s and are so confident in its ruggedness that we back it with our industry-leading warranty.
SLx 1-10: Reticles
At Primary Arms, we’re big believers in the innovation of reticles in rifle optics. A bad reticle can hamstring even an otherwise brilliant scope, while a good one enables users to be faster, more precise, and more effective. Since the SLx 1-10x SFP is our very first 1-10x optic, we had to develop some new reticles to take advantage of the unprecedented magnification range.
After extensive research and development, we’re proud to introduce the ACSS® Raptor 5.56 M10S and ACSS® Griffin M10S reticles.
Both are implemented in a second focal plane design, meaning that the reticle stays a consistent size regardless of changes in magnification level. While many of our scopes use first focal plane reticles, for a scope with this wide of a magnification range, an FFP design would run the risk of being either too small to be useful at 1x or too big to be precise at 10x.
With an SFP reticle, it’s always the perfect size, although as a result users will have to zoom in to maximum magnification for accurate target ranging and holds. It’s a small drawback; even with an FFP reticle, you’ll generally want to zoom in as much as possible when target ranging for more precise measurements.
We’ve talked a lot about the benefits of increased magnification and the SLx 1-10x’s capability at extended ranges, but for an LPVO that’s all about versatility, short-range performance is equally important. This is one area where an SFP reticle is beneficial; many FFP 1-10x reticles are little more than a ragged dot at minimum power and rely heavily on powerful illumination to be usable.
Both our ACSS Raptor 5.56 M10S and Griffin M10S reticles are easily usable with or without power at 1x, thanks to the second focal plane design and chevron-and-horseshoe aiming point. In these reticles, the chevron provides an infinitely small aiming point for high-precision shots, while the horseshoe offers a rapid aiming solution at CQB distances. Both segments can be illuminated to help draw the eye and increase contrast but are bold enough to be usable on their own.
For unknown-distance target engagement, both reticles feature auto-ranging and MIL-based ranging solutions. The auto-ranging brackets on either side of the horseshoe offer rapid range estimation for full or half-sized targets (such as an IPSC target) based on height, while the vertical stadia can be used to range targets based on width.
In the Raptor 5.56 M10S, a simple MIL-ranging system is built into the farthest auto-ranging brackets on either side of the reticle. In the Griffin M10S, the MIL-grid system can be used for ranging as well.
This is where the reticles begin to diverge. The Raptor 5.56 M10S features a BDC with auto-ranging and intuitive holdovers with subtensions based on 5.56 ballistics. In addition to ballistic drop subtensions out to 800 yards, the reticle also offers wind holds for crosswinds of up to 20 miles per hour.
The Griffin M10S, on the other hand, features a full MIL-grid, making it fully compatible with just about any cartridge, barrel length, or ambient environment. Several of the top MIL stadia include auto-ranging features as well, making it just as quick to estimate a target distance and engage with unerring precision.
Both reticles offer moving target leads on the left and right of the horseshoe for targets at intermediate distances.
Wrap Up
1-10x scopes are the new frontier of LPVO technology, and we’re excited to bring our very first 1-10x optic to market. The SLx 1-10x SFP is the perfect scope for any multi-role or all-purpose rifle, offering enough magnification for nearly any cartridge that can fit in an AR-15 frame while still being fast at 1x for CQB.
This new scope marks a new level of versatility and value for users that want to do more with their rifles. You never really know what life is going to throw at you, but with the SLx 1-10x, you can be prepared for anything.
