MCX Zero Retention Clamp SD
The Patent Pending Arisaka Zero Retention Clamp (ZRC) greatly reduces zero shift for lasers and iron sights that are mounted on the handguard of the MCX Virtus. This version is designed for the MCX Virtus chambered in 300BLK or 5.56mm with either the Sig Sauer SD handguard or Midwest Industries Suppressor M-Lok handguard.
The MCX Virtus handguard is secured to the receiver by a friction fit slot on each side near the extended receiver top rail and a single steel fitting held in place by the front takedown pin. This allows the handguard to flex significantly, causing a laser or front sight zero to change when minor pressure is applied to the handguard. A shift of 5 mils or more is possible by pushing on the handguard with your support hand while the rifle is shouldered. Additionally, the zero does not always return to it's original position once pressure is removed from the handguard.
Sig Sauer has resolved this problem on the new MCX SPEAR by adding a fastener on each side of the handguard that securely anchors it to the upper receiver. The Arisaka ZRC plays a similar role for the MCX Virtus by adding exterior clamps that thread into a special U-bracket. The U-bracket engages the extended upper receiver underneath the handguard. This secures the handguard tightly to the upper receiver across two axis, greatly reducing or even eliminating zero shift. The U-bracket does not touch the barrel or gas system, preserving the free-floated barrel.
The ZRC clamps are contoured to provide minimal interference with the user's hands while gripping the handguard. On the SIG Sauer SD handguard the clamps fit over the rhombus shaped vents, while on the Midwest Industries suppressor M-Lok handguard they occupy one M-Lok slot in the top row. Each clamp is labeled for the side and orientation, making installation easy.
1. Torque spec: 15 inch lbs. While we recommend using a calibrated torque wrench, approximately 15 inch lbs of torque can be achieved by inserting the long end of the included Torx L-key into the screw head and holding the short end in your fingers, then tightening firmly. Exceeding 15 inch lbs risks stripping the screw head and/or damaging the handguard. Arisaka is not responsible for any damage caused by improper installation.
2. The ZRC must be uninstalled before removing the handguard from the rifle.
The ZRC clamps and U-bracket are CNC machined from 6061-T6 aluminum and MIL-A-8625 Type III hard coat anodized.
Made in the USA.