GBRS Group Lerna Mount Kit

The Lerna is the Hydra with the accessory platform removed. Same 2.91 inch optic centerline, same 6061-T6 body under a Type III Class 2 hardcoat anodize, same 17-4 PH H900 stainless clamp bar and screws in Melonite QPQ, same 45 inch-pound clamp torque. What changes is that the elevated MIL-STD-1913 rail above the optic is gone, and with it about 1.7 ounces and half the price.

That tradeoff is the right one for most buyers. The 2.91 inch height exists so a shooter in helmet-mounted night vision, a CBRN mask, or an active headset over armor can get behind the optic without collapsing into a chin weld, and none of that requires a light or laser bolted to the mount. Handguards have M-LOK slots for that. The Hydra's accessory rail earns its cost on short PDW and SMG hosts where the handguard is already full; on a 14.5 or 16 inch carbine it is mostly extra money and extra weight.

GBRS machines the Lerna for the Aimpoint Micro T-2, Aimpoint Duty RDS, Aimpoint ACRO, EOTech EXPS, EOTech XPS, and Trijicon MRO, each in Black or Flat Dark Earth. The ACRO build is the notable one: the Hydra line does not offer it. GBRS publishes 4.8 ounces for the Aimpoint Micro and ACRO builds and lists the EOTech and MRO builds lighter still, so every version undercuts the Hydra by well over an ounce. As with the Hydra, a magnifier will not co-plane at this height without GBRS's separate 2.91 FTC mount. Designed, manufactured, and assembled in the United States.