MPN: 05-278B / 05-278S / 05-283B / 05-283S / 05-315B / 05-315S


  • One-piece free float design
  • Full top Picatinny rail for optional attachments
  • Integrated M1913 picatinny rail sections at the fore of the rail in the 3, 6 and 9 o’clock positions
  • Updated version of the proven Geissele Barrel Nut design for ease of installation and superior rigidity
  • M-LOK slots at 1, 3, 6, 9, and 11 o'clock positions
  • Compatible with most low-profile gas blocks
  • Total of four quick disconnect sling socket at the 3 and 9 o’clock positions
  • Available in Black or Desert Dirt Color (DDC)


  • Material: 6061-T6 Aluminum
  • Finish: Type 3 Hardcoat Anodized
  • Length (When Installed): 9.3-Inch, 13.5-Inch, and 15-Inch
  • Weight (With Barrel Nut):
    • 9.3-Inch: 11.6 oz.
    • 13.5-Inch: 14.8 oz.
    • 15-Inch: 16 oz.
  • Inside Diameter: 1.35"
  • Outside Diameter:
    • Height: 2.3"
    • Width: 2.11


  • Mil-Spec AR-15 uppers


  • 1x Geissele MK4 Super Modular M-LOK Handguard
  • 1x Barrel Nut
  • 1x Press Nut M6
  • 2x Mounting Screw Washers
  • 2x Socket Head Shoulder Screws
  • 2x Set Screws
  • 1x 5/64 Allen Wrench
  • 1x 4mm Allen Wrench

*Barrel nut wrench not included


The Geissele MK4 rail is the ultimate M-LOK Picatinny rail for serious shooters. Rugged yet lightweight, it accomplishes its mission effectively.

Streamlined For Installation, Updated For Durability

Made from tough 6061-T6 Aluminum, then finished with Type 3 Anodized Hardcoat, you can rely on the MK4 rail to hold your tactical accessories in place when you need them the most.

The MK4 rail is congruous with the majority of low-profile gas blocks.

Geissele updated their barrel nut design in the MK4 rail to offer improved rigidity and simplify installation.

Note that you will require a barrel nut wrench for proper and efficient installation.

A Rugged and Highly Tactical Picatinny Rail

Geissele's understanding of the tactical needs of shooters resulted in this supreme rail design; this free-floating one-piece rail was engineered to vent heat while remaining durable yet remaining low weight. The MK4 rail does what you need it to and does it well.

The MK4 rail features a full top Picatinny rail for attachments you may want to install. Magpul's M-LOK slots are found at the 1:00, 3:00, 6:00, 9:00, and 11:00 points, and four quick disconnect sling sockets are located at the 3:00 and 9:00 points.

Geissele's MK4 rail was strategically engineered to improve your disassembly and reassembly, allowing you to perform maintenance more efficiently.

*Due to the chemical process that takes place during Type 3 Hardcoat, the finish on the product can vary from one to the next, even if it is the same batch.

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