About Airsoft Rail Systems and Attachments
When it comes to Airsoft, there are 3 common types of attachment interfaces, also known as "rails", found on Airsoft guns. The function of an Airsoft rail is to allow accessories to be mounted, ranging from red dot sights and scopes to vertical foregrips, bipods, tactical flashlights and PEQ laser units and even grenade launchers!
What are the different Airsoft rail types?
20mm Picatinny RIS/RAS rails
20mm Picatinny rails, also known as "Pic rails", "RIS" or "RAS" is the most common type of rail found on Airsoft guns. Most Airsoft replicas of modern firearms have a 20mm Picatinny rail on the receiver, intended to allow red dot sights, scopes or iron sights to be mounted.
Others may also be equipped with 20mm rails on the handguards, designed to facilitate the addition of accessories such as tactical flashlights for navigation and distraction, laser aiming modules for faster target acquisition or vertical/angled foregrips for improved comfort. The shape of the 20mm Picatinny rail can be quite uncomfortable to hold by default, and as such many skirmishers add what are known as "rail covers", polymer pieces designed to protect the rail from damage and provide better ergonomics.
M-LOK Rails
M-LOK rails are a more recent development, based on the Magpul MOE attachment system and using the principle of "negative space attachment". Instead of the raised protrusions found on 20mm Picatinny rails, M-LOK rails make use of rectangular ports to mount accessories which result in reduced weight and improved comfort when no accessories are mounted.
Being a more modern system, M-LOK accessories are not yet as prevalent as those for 20mm Picatinny, but you can mount the more common Picatinny accessories using 20mm Picatinny rail adapters for M-LOK. M-LOK has its own accessories too, including flashlight mounts, sling points, vertical and angled grips, rail covers and bipods, all of which can be mounted directly to the M-LOK slots on an M-LOK handguard.
KeyMod Rails
KeyMod rails were conceived around the time of M-LOK, as an open-source negative space attachment system used by a wide variety of brands. KeyMod uses keyhole-shaped slots instead of the protruding "teeth" found on Picatinny rails, reducing weight and providing a slimmer, more comfortable handguard to hold with no accessories mounted.
KeyMod accessories such as flashlight mounts, sling mounts, bipods, front grips of both the vertical and angled variety and rail covers are available for direct mounting, but as with the M-LOK system, these accessories are less common than the 20mm Picatinny variety. Like M-LOK, KeyMod can also be used to mount 20mm Picatinny accessories using 20mm rail adapters for KeyMod, meaning if you upgraded to KeyMod you can still use your Picatinny accessories.
Airsoft Rail Systems FAQ
Do Airsoft guns use Picatinny rails?
Yes! Most Airsoft guns have a 20mm Picatinny rail, most commonly on the receiver but they can also be found on the handguard and the frames of many modern pistols. Aftermarket Picatinny rails can also be purchased and added to guns which don’t come with one. You can find out what rail type your Airsoft gun has by referring to the “Specification” section of our product descriptions.
What is the handguard for my M4?
With an M4, it can vary quite widely. 20mm Rails can be identified by their shape, hexagonal in profile with protruding teeth. M-LOK Rails have rectangular slots instead of teeth, and KeyMod rails use keyhole-shaped slots. Many M-LOK and KeyMod rails also have a 20mm rail on their upper surface. Some M4s also come with polymer “M4A1” type handguards which can be identified by their two-part design, polymer construction and ribbed gripping surfaces.
Is M-LOK compatible with KeyMod?
In most cases, no, but some accessories come with mounting apparatus for both M-LOK and KeyMod. You can find information on compatibility in the “Specification” section of our product descriptions.
What handguard does the military use?
At the time of writing most militaries still use 20mm Picatinny handguards as they are seen as the simplest solution, although many militaries issue rifles with M-LOK or KeyMod handguards to their Special Forces. The British Army is currently transitioning to KeyMod and M-LOK on the SA80A3, and the US Army’s next-gen combat rifle, the XM7 (SIG Spear), is equipped with an M-LOK handguard.
What is the best looking handguard for M4s?
This one is up to you! Though beauty is in the eye of the beholder, we are quite partial to the MK16 URGI M-LOK handguard, the DD MK18 RIS II 20mm Picatinny handguard and the Noveske NSR KeyMod handguard. We also love the Troy TRX handguard but these are becoming very rare!
What handguard does the MK18 use?
Both versions of the MK18 use 20mm Picatinny quad-railed handguards. The original MK18 MOD 0 uses the 7-inch KAC RAS 20mm handguard but the more modern MK18 MOD 1 uses the Daniel Defense 10-inch MK18 RIS II free-floated 20mm handguard.
Is M-LOK better than 20mm Picatinny?
Yes, and no! The M-LOK system offers reduced weight compared to 20mm Picatinny and in most cases, a more ergonomic profile. 20mm is often seen as more affordable as accessories tend to be cheaper and rail adapters are not required to mount tactical flashlights and lasers.
Do I have Picatinny or Weaver rail?
Visually, these two rail types are very similar but you can tell them apart if you know what to look for. A Picatinny rail can be identified by the squared-off recesses in the rail as opposed to the rounded recesses of a Weaver rail. Weaver accessories can be mounted on a Picatinny rail, but the reverse is not true without modification to the rail.
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![Buying Guide: Rail Systems]()
RIS, M-LOK, KEYMOD, URX!? We get it, there's a big mix of rail systems and attachment interfaces, but we're here to help you identify what each rail system is and decide which rail system works best for you.
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![Buying Guide: Rail Covers, Grips and Hand Stops]()
If you are wondering why Airsoft Guns touted as ergonomic have sharp cheese-grater-esque bits all over them, and how to save your hands the trauma of having to hold these sharp edges during a firefight, check out this guide on Rail covers, grips and hand stops!
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![PBTV Knowledge Base | Airsoft Rail Systems Explained!]()
Wondering what a rail system is? If so, join us for this PBTV Knowledge Base video where we show off the various different rail systems available to Airsofters and talk about what each is best at!
