AS Designs Geissele HK MR556 Pre-Cut Trigger

AS Designs starts with the Geissele HK MR556 two-stage trigger and machines the clearance required for its ARC-Fire selector. The result preserves the HK-specific Geissele hammer and two-stage pull while avoiding a do-it-yourself trigger cut. AS Designs lists a 2.75 to 3.0 lb first stage, a 1.5 to 1.75 lb second stage, and a 4.25 to 4.75 lb total pull.

The trigger is a companion to the HK-specific ARC-Fire V2 selector kit, not a complete forced reset mechanism by itself. AS Designs' MR556 install guide says the Geissele MR556 hammer is full size, so the separate lever blocker is not required on this path. The same guide covers MR556, MR223, HK416, and BRN-4 carrier versions, while the product page limits the trigger itself to HK MR556 and semi-automatic HK416 applications and expressly excludes MR762.

This is a modified trigger sold by AS Designs rather than a standard Geissele shelf SKU. The exact pre-cut version costs $470 direct. Brownells carries the unmodified Geissele HK MR 5.56 trigger, but that product still lacks the ARC-Fire clearance cut and is not an exact substitute.