Geissele Automatics Super Modular MK4 15" Rail Handguard - M-LOK - Black

Manufactured by Geissele Automatics
SKU: 05-315B
MPN: 05-315B
Manufactured by Geissele Automatics
1 Review

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Standard orders will ship out within 2 business days or less. FFL orders will ship within 5 business days or less as long as we have the information for the transfer destination.



The Geissele Automatics Mk4 Super Modular Rail is an ultra-light purpose-built free float handguard for the AR-15 platform. This modular rail features M-LOK slots on five surfaces for your favorite accessories that double as excellent heat venting to help your rifle run cool. The Mk4 features integral M1913 rail sections at the 3, 6, and 9 o'clock positions at the muzzle end to accommodate weapon lights and bipods. The included proprietary barrel nut increases surface contact, increasing accuracy and repeatability of zero should the handguard be removed during maintenance.

  • Does not include barrel nut wrench
  • 15" handguard weighs just 15.4 oz.
  • Durable black hardcoat anodized finish.
  • Full-length M1913 picatinny top rail.
  • M-LOK slots on five sides.
  • Includes barrel nut.
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Accessory AttachmentM-LOK
BrandGeissele Automatics
FinishHardcoat Anodized
Gas System LengthExtended Rifle
Handguard Length15.00 in
Inner Diameter1.35 in
ManufacturerGeissele Automatics
MaterialAluminum - 6061-T6
Weight15.4 Oz

WARNING: This Product can expose you to chemicals which is known to state of California to cause Cancer and Reproductive Harm. For more information, see

Ratings & Reviews

1 review

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Worth. Every. Penny.


So lets just get this out of the way first- it's expensive. Yep. And you get what you pay for. I have had all kinds...Troy, LaRue, YHM, MI. Geissele wins, hands down. There isn't a single part of this rail that isn't extremely well thought out and executed. From the mounting system to the machining to the finish, it's all absolutely first-class. So many of the things we buy these days are a compromise, and I am here to tell you this rail exceeds my expectations. Either this Mk4 or the Mk8, it's just a matter or personal preference, but either way you cannot go wrong.