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With countless accessories, upgrades, and spare parts options available, the AR-15 is one of the most customizable weapons platforms in the world.
However, the type of handguard you choose can significantly impact the way you accessorize your AR-15.
Why Are Handguards Important?
In classic hunting and service rifles with a one- or two-piece wooden stock, the fore-end or fore-stock provides an additional point of contact—a surface for you to grasp with your non-dominant hand to support the barrel. At the same time, the fore-end protects your hand against the heat from the barrel during extended firing sessions.
In addition, the fore-end provides a mounting point for a sling swivel, bipod, or foregrip. In modern military rifles, handguards fulfill the same role as the fore-end.
Handguards can be removable, modular, and often encircle the barrel. In gas-operated weapons, the handguards also protect the gas tube, piston, or operating rod from impact damage.
There are numerous AR-15 handguard types to choose from, each offering different advantages or uses.
AR-15 Handguard Types
When the AR-15 first entered commercial production, its handguards were triangular, consisting of two pieces. These handguards had holes in the top and bottom to promote air circulation and contained aluminum reflectors to absorb heat.
Later, the triangular handguards were replaced by the familiar circular vertically ribbed handguards on the CAR-15, M16A2, and later M4. While these are still familiar to AR-15 owners, the accessories market for the AR-15 rifle pattern has spat out so many handguard choices that you’re not limited to what was available 40 or 50 years ago.
One of the disadvantages of the triangular and circular handguards is that they don’t readily enable the attachment of accessories. In the 21st century, there are numerous accessories available to the self-defense practitioner, hunter, or competitive target shooter, designed to enhance stability, speed, or augment the function of the rifle in some way.
How to Choose a Handguard?
If you prefer a drop-in handguard set, you’ll need to choose handguards that are compatible with the gas system length of your rifle, as these handguards connect to the gas block in the front. However, two-piece military handguards, while durable, are not free floating.
Free floating means the handguard does not contact the barrel or gas block, reducing interference with barrel vibrations. Free-floating handguards are usually monolithic—i.e., made from one piece—and attach to the rifle by the barrel nut in the rear. While there is no length requirement, the free-floating handguard should, ideally, cover the gas tube.
If your rifle has a traditional set-up, you’ll need to remove the muzzle device and gas block/front sight to slide the free-floating handguard over the barrel. If your rifle has a low-profile gas block, removal may not be necessary. Many free-floating handguards have dedicated barrel nuts that replace the delta ring.
Some free-floating handguards extend to the muzzle, increasing the available rail space for accessories. While not as durable as mil-spec two-piece handguard sets, free-floating designs can increase inherent accuracy.
If you’re interested in building a match rifle, this is one of the best AR-15 handguard types you can choose.
M-LOK, KeyMod, or Picatinny?
One of the advantages of the AR-15 rifle pattern is its compatibility with a wide variety of accessories. However, you need to be able to attach accessories to your weapon to realize its benefits. Traditional AR-15 handguards offer limited flexibility here. A market in modular, accessory-compatible handguards has developed, thanks to the work of multiple manufacturers.
This has led to the emergence of two alternative systems to the traditional Picatinny rail: M-LOK and KeyMod. In breaking down these three systems, it’s worth discussing each one individually.
In 1995, the Picatinny rail—an accessories mounting system for small arms—was standardized by the United States Army as MIL-STD-1913. Today, the Picatinny rail remains the standard for mounting accessories to rifles, from optical sights and flashlights to laser aiming modules and foregrips.
However, the full-length Picatinny rail has begun to fall out of favor on handguards because it adds weight and bulk. In addition, the quad-rail configuration that became popular on the AR-15 platform adds sharp edges that often require rail covers to be comfortable to hold or carry.
The solution, then, has been to substitute slots and adapters, reducing the amount of material on the handguard for a sleek, streamlined surface.
The M-LOK or Modular Lock type of rail interface system was designed by Magpul Industries, a company famous for manufacturing AR-15 magazines and accessories. M-LOK allows you to attach short Picatinny rails only where you need them, reducing weight and bulk and leaving most of the handguard smooth.
M-LOK offers increased flexibility regarding which end of the slot you want to attach your accessory to, and adapters aren’t necessary with many Magpul-brand products.
You can find handguards, upper receiver assemblies, and complete rifles featuring both systems; M-LOK has more widespread industry and military support than KeyMod.
The KeyMod rail interface system uses slots, not unlike those of the M-LOK system. However, the principal difference between the two systems is in the design of the slots.
In the KeyMod system, the slots are keyhole-shaped, hence the name, and function similarly to a door chain. You insert the nut into the large hole, slide it forward into the narrow part of the slot, and fasten it in place.
Although KeyMod doesn’t allow you to fasten rails to either end of the slot, it does have the advantage of self-aligning.
Aside from the lack of rail material in both M-LOK and KeyMod handguards, the slots further reduce weight and contribute to the circulation of air, keeping the barrel and gas tube cool. Unfortunately, the open handguard design also permits the ingress of dirt, mud, sand, and other foreign debris, potentially clinging to the rifle and weighing it down.
Picatinny rail handguards are still the standard, but slot systems are gaining a foothold. If you want a negative-space rail system that keeps weight to a minimum, you should consider selecting an M-LOK-compatible handguard.
KeyMod handguards are functional and readily available; however, for secure attachment, M-LOK has the advantage. SOCOM’s stress testing suggests that KeyMod’s success rate at keeping accessories secured is lower than that of M-LOK when subjected to impact.
If you’re building the most lightweight rifle you can is your goal, skeletonized handguards are also an option. In these designs, which are typically free floating, manufacturers mill slots into the handguard to reduce weight. These can be highly stylized.
Regardless of the type of shooting you’re interested in, accessory-compatible handguards can significantly improve your performance on the range and in the field. Once you determine your needs in this regard, you’ll have a boatload of options to sort through.