MREX Past Present and Future

Welcome to the blog!

This first blog we wanted to discuss our staple product line, the MREX rail for the FN SCAR family of firearms. In particular we will be discussing their history, and comparing the different models. Throughout this article I will also sprinkle in some easter eggs about the long awaited MREX20 (for the SCAR 20) and the different models that will be released, as well as the design changes we will be incorporating into a Mod3. I will do my best to structure this post in order from old to future models so feel free to jump around from paragraph to paragraph. Let’s begin! 


The MREX (Modular Receiver Extension) for the FN SCAR is the premier handguard replacement that has successfully served the shooting community and Special Operations units in combat for over 9 years. In the lifetime of the MREX there have been 7 different models spanning 2 generations. There are 2 variations of the Gen1: the Gen1 Super Modular Rail (SMR) and the Gen1 MLOK. The first in the lineup is the Gen1 SMR. Now there is a little confusion on the internet about the SMR mounting system, but my understanding is it was essentially developed by HK and later adopted by Geissele (I will include a link below if you’d like to learn a little more about the SMR mounting system). The SMR style was one of the first widely adopted rail designs that aimed to dethrone picatinny, very similar to Magpul MLOK and VLTOR KeyMod at the time. However, SMR did not take off with the same voracity that MLOK or KeyMod did. With MLOK quickly becoming the industry standard we decided to capitalize on the “negative space” advantages. This led to a quick redesign of the Gen1, replacing a portion of the SMR mounting system with MLOK. Due to the profile of the rail the Gen1 MLOK still featured a modified SMR pattern on the back half of the rail.  

Geissele Super Modular Rails – An Overview – AR Build Junkie


 The biggest leap in 5 years, the Mark Two (MkII). Due for an upgrade, the MkII delivered a lighter, stronger rail with a completely different yet familiar look and feel. The MkII features a wider profile to aid in manipulation, ventilation and configuration, redesigned to be completely covered in MLOK. The front picatinny rail found on the Gen1 was replaced with MLOK, the offset 45 MLOK slots were moved to better suit accessories and a single MLOK slot was added on each side of the gas block. The MkII also featured full length MLOK on the sides instead of the 50/50 MLOK/SMR found on its predecessor This redesign reduced the weight by an additional 2 ounces compared to the Gen1. There is also one more huge, and often unrealized advantage, less hardware. During testing and design, we realized that we could remove 2 of the mounting fasteners (40% of the hardware) with zero loss in strength or rigidity. 


 Now we can’t just do a redesign and call it quits, we had to find a way to offer more options to better suit the needs of both military and civilian users. So, when we released the MkII we not only tweaked the lengths offered, but we also added a third length to the lineup. Each length nomenclature indicates how far past the receiver the handguard extends; this measurement is from the front face of the picatinny rail on the upper receiver to the very front of the MREX. The 6.5, the longest model, did not change from generation to generation. The Gen1 4.9 was reduced to a total length of 4.25 inches and became the intermediate option with the addition of the MkII 2.2. The shortened 4.25 was developed to better suit the needs of issued Mk17s with 13-inch barrels and FN issued suppressors. With SBRs in mind the MkII 2.2 is ideal for use with 10-inch barrels. All MkII rails have the added benefit of staying attached to the barrel if barrel reconfiguration is required. These lengths, with the exception of the MREX-P and MREX20 (spoilers), will carry through into future generations. 


Now some things are very subject to change but let’s talk about the foreseeable future of the MREX family. Here at Kinetic, we are always trying to evolve our product lines to meet the needs of our customers. The MREX has already been through three iterations and found itself in the hands of some special operations groups defending our country, the common man defending their homes and sports shooters alike. With such a broad range of applications, we need to keep pace to provide the most versatile and reliable handguards possible. 

The MREX has been here for almost a decade, and it’s time to once again advance. Over the years, we have received tons of feedback from you all – and we hear you. We are proud to announce we are actively working on a Mod3 (Gen1, MkII, Mod3, not confusing at all, right?). While I unfortunately can’t give away too much detail until we get closer to release, you can be sure it is on the way. It will feature a healthy blend between past and present, combining the best of both worlds from each. The Mod3 will maintain the features you know and love while also increasing compatibility with other aftermarket accessories you may already have. At the same time, you SCAR 20S fans can also expect to see some love with the release of the MREX20 (MREX for Scar 20, make sense?). While I continue to throw very vague information at you, all I can offer is “Precision Rifle Shooting” (PRS). There will be included features to accommodate more long range applications in both the Mod3 and the MREX20. As the SCAR continues to evolve so will the MREX.