When it comes to the AR-15 platform, flexibility is king. You can choose from hundreds of accessories and options for each part that makes up your weapon, from trigger to stock. For many types of accessories, you’ll need to attach them to a rail.
So when choosing the right rail for your gun, you need to understand the different types of rails and how they work in different situations. Not every rail system is the same, so if you’re looking for a high quality, long-lasting and useful rail system, read on.
What You Can Attach to a Rail
What you can mount on your gun depends on the type of rails that you use. There are various kinds of handguards which come with rails. Drop-in handguards are easy to install and quite inexpensive, but they usually offer fewer mounting options. Railed drop-in handguards offer more mounting options, including bipods, grips, lights, or lasers, but not optics.
Free-floating handguards with quad rails allow for the mounting of bipods, grips, lights, or lasers and optics, and are a very accessory-friendly type of handguard. However, quad rails are usually heavy and more expensive as they require more machining to produce. They are also more difficult to install on the weapon compared to the simple drop-in handguards. A third kind of rail is for the carry handle, to allow for optics that work well with AR's with A2 uppers.
What Everyone Wants in a Rail System
There are some qualities that everyone desires in their AR-15 rail systems. Think about the core purpose of the handguard and rails, and you can identify what you need. These include weight, stability, ease of use, looks and mounting options.
The weight can definitely be a factor when choosing a rail system, as it will add to the overall weight of the gun. You will want to avoid adding too much weight because you will also be adding accessories and parts to the rail later.
Some rails are more stable than others. Free-floating handguards, for example, are going to be more stable than drop-in ones, affecting your accuracy as a result. Choosing a good free-floating handguard often involves choosing the ones with the right rails, among other things. Quad-rail handguards also offer more mounting choices compared to the MIL-STD 1913 (Picatinny) rails on some drop-in handguards.
Ease of use includes both installing the rails and then mounting your accessories on top of them. Generally the drop-in rails are a cinch to install, but free-floating ones may be more difficult.
Looks can also be deciding factor for you. Are you seeking a classic, tactical or military look for your AR-15? Whichever one it is, there are a lot of options out there for you.
M-LOK vs Keymod Rails
The MIL-STD 1913 (Picatinny) specification has been around since the 1980s and is very commonplace. It is an excellent accessory rail system, but some gun users dislike the extra weight that the Picatinny adds. The Picatinny also needs a rail guard, which is another factor for users.
Users have had new options in the form of Keymod (since 2012) and M-LOK (since 2014) mounting rails, which are increasingly available. Over the last few years, these two new systems have become very popular as an alternative to the classic Picatinny rail. They both use machined cutouts instead of "ridge and groove" for attaching accessories, resulting in a lighter handguard that is simpler to machine.
One of the most hotly contested arguments in the firearm industry is which is preferable, KeyMod or M-LOK.
KeyMod rails consist of rows of keyhole shapes that allow KeyMod-compatible accessories to mount into place on the handguard. To attach an accessory, users line up the lugs on the accessory with the round part of the keyhole then slide it forward and tighten the screws. This is an open-source system that manufacturers can use to build into accessories without paying royalties to the original designers.
Magpul introduced the Modular Lock, or M-LOK, system that uses slots instead of keyhole shapes and benefits from attachment lugs on accessories that are t-shaped and bi-directional. This design allows M-LOK compatible accessories to mount at the front or rear of the slots. The M-LOK is free to use. But unlike KeyMod, it requires approval from Magpul before manufacturers can market their accessories. This allows better quality control for the finished items.
The M-LOK system has gained in popularity over the KeyMod since its introduction, helped by the fact that it has been found to be the more durable system in comparison to the KeyMod system in testing by the Naval Surface Warfare Center.
While both systems have been very successful, you should pick the one that will allow you to mount the accessories you require and which will fit the accessories you may already own. However, M-LOK rails would be a good place to start if you haven’t bought any accessories yet.
Quick Comparison Chart of the Best Rails for the AR-15
Magpul AR-15 Picatinny M-LOK Rail
ALG Defense AR-15 Ergonomic Modular Rail V2
Kinetic AR-15 Picatinny M-LOK Rail
Midwest Industries, Inc. - AR-15 Picatinny M-LOK Rail Aluminum
Midwest Industries, Inc. - AR-15 Picatinny KeyMod Rail Aluminum
Reviews of the Best Rails for the AR-15
To help you make your decision, we’ve listed some of the best rails for your AR-15 build which will meet a wide range of budgets and needs. Keep in mind the key factors of mounting options, weight, stability and ease of use when making your decision.
This combo rail from the creators of the M-LOK system allows you to attach MIL-STD 1913 Picatinny rail-mounted accessories to your M-LOK rail. Sections come in either aluminum or polymer. The color is matte black and sections come in various lengths such as 3 Slots – 1-1/2" (3.8cm) OAL, 5 Slots – 2-3/8" (6cm) OAL, 7 Slots – 3-1/8" (7.9cm) OAL and 9 Slots – 3-7/8" (9.8cm) OAL.
This rail is a really good value and works with many guns. It’s consistently stable (as long as it’s correctly mounted). And of course since it comes from Magpul, it means you’re getting a product right from the original maker.
The Ergonomic Modular Rail V2 from ALG allows M-LOK accessories to be mounted on the rail at the 2, 4, 6, 8 and 10 o’clock positions. The difference between this version and the V1 is that the V2 has a machined M1913 Picatinny rail section near the muzzle end that is ideal for attaching M1913-compatible accessories. It provides a rigid platform for weapon accessories like optics and the weapon barrel is free floating.
The material used is aircraft grade 6061-T6 aluminum. A 2’’ long aluminum barrel nut is available for purchase separately and is required for installation. This rail is available in various sizes such as 10’’, 12’’, 13’’ and 15’’. And it’s easy to remove and reinstall as needed.
This compact and light QD mounting system is designed for easy and quick installation and can be mounted with any M-LOK rail system. It uses 2 spring-loaded wedges to hold the accessory into place, making the mounting and dismounting extremely fast.
The Kinetic is 1.68″ (42.8mm) long, .82″ (20.9mm) wide and .41″ (10.5mm) in height. It comes in black anodized finish and weighs 0.8oz.
Like the typical M-LOK system it’s extraordinarily easy to install or remove accessories.
The 1913 Picatinny rail sections are mounted on M-LOK compatible and come in 3-slot, 5-slot, 7-slot and 9-slot lengths. They are made from 6061 aircraft grade aluminum and are hard coat anodized. All mounting hardware is included and it’s easy to install. The rails come in black and are reasonably priced.
You can use these rail sections to attach onto any KeyMod rails and give accessory mounting space. They are made from 6061 T6 aluminum, in a matte black finish. They are available in both a 2.1" segment with 5 slots and a 3-3/4" segment with 9 slots.
Why Use Riser Rails
Riser rails, also known as riser mounts, are used to raise the scope or optics enough so that there is no interference from objects in front such as a handguard. Like other rails, they come in a variety of materials, colors and specifications to allow different types of accessories to be mounted. Generally they are designed for Picatinny-style accessories but other types can also be found.
Having your optics at the right height is important for a good cheek rest and a rule of thumb for scope height is to have your scope mounted as low as possible, without any portion of the scope touching the barrel or any portion of the rifle.
Quick Take: Best AR-15 Riser Rails
These riser rails are the best options for the AR-15:
Reviews of the Best Riser Rails for the AR-15
Like accessory rails, riser rails for the AR-15 are plentiful. The best riser rails will give a great fit and suit your optics as well as shooting style while providing the stability that your optics require.
This small and compact mini-riser raises your optics and lasers by 0.5’’ and fits Picatinny rail systems. It is constructed of aircraft-grade aluminum and hardcoat anodized for durability. It is available only in black. Two cap screws clamp the riser securely to the gun’s rail. It is 15⁄16” (3.3cm) long, 1¼” (3.1cm) wide, and weighs 1.1 oz. (31g).
While this mini riser is lightweight, compact and inexpensive, it’s not suitable for optics that need more clearance.
This riser from Brownells clamps to a flattop AR-15 receiver and raises the mounting height for optics by .750". The riser accepts both Picatinny and Weaver-style rings. A smooth, curved front and rear contours on the underside provide a streamlined appearance, reduce weight, and minimize the chance of catching on gear.
It is made from 6061 T6 aluminum, and hardcoat anodized for durability and comes in in matte black. It is approximately 5” (12.7cm) long, 1” (2.5cm) wide at the base, and .975” (2.45cm) high overall. It weighs 4.8 oz. (136 g).
This riser rail will mount the Razor Red Dot as well as other optics that mount to a Picatinny base. It provides a lower 1/3 co-witness height. Made from aluminum, this riser is only available in black. The overall length is 2.540" with a rail of 2.230". The top of flattop to the top of the riser is 0.6" with an overall height of 0.875".
It’s accurate but still easy to adjust. Vortex has definitely put together a sturdy, quality product although it’s on the expensive side.
Within the vast world of AR-15 accessories, accessory rails play a big role in helping you get the shooting experience that you desire. Customizing your gun for the accuracy, look and features that will give you the edge in combat, target shooting or hunting means having the right type of rails to fit all the accessories.
M-LOK and KeyMod are both popular options for rail types and have proven their utility in the market for several years. You cannot go wrong with either one, as long as you check that your accessories will work with the rails.