FRT-MR3 (Flat) Single-Stage (3-Position) Forced Reset Trigger for the HK MR223 & HK MR556

If you run an HK MR223 or MR556, you already know the platform demands precision components. The FRT-MR3 (Flat) Single-Stage (3-Position) Forced Reset Trigger delivers a mechanical advantage that changes how you work the trigger shoe. This is not a gimmick. Rare Breed engineered this drop-in unit to function with the specific bolt carrier geometry and hammer profile of the HK family. The flat face gives you consistent finger placement every time, and the three-position selector gives you safe, semi-automatic, and forced-reset operation. No guesswork, no unreliable binary nonsense. This trigger resets by the bolt carrier forcing the shoe forward, which means your follow-up shot cadence is dictated by the reciprocating mass, not by how fast you can lift your finger.

Overview

The FRT-MR3 (Flat) Single-Stage (3-Position) forced reset trigger for the HK MR223 & HK MR556 is purpose-built for shooters who want increased cyclic control without modifying the lower receiver. Rare Breed started with a machined steel housing, added a flat trigger shoe with a crisp single-stage break, and integrated the three-position selector that toggles between safe, semi-automatic, and forced-reset modes. The forced-reset function uses the bolt carrier’s forward travel to reset the trigger, which allows the shooter to maintain a stationary finger while the trigger cycles itself. This is the same mechanical principle that made the FRT-15 a known quantity, but optimized for the HK MR223 and MR556 platform.

Features & Specs

• Three-position selector: Safe, Semi-Automatic, Forced-Reset. The forced-reset position uses bolt carrier travel to mechanically reset the trigger shoe forward, enabling rapid follow-up shots while maintaining a stationary trigger finger.
• Flat single-stage shoe: The flat face reduces finger slip and provides a consistent pull angle. Single-stage break is crisp with no take-up, and the reset is audible and tactile when the bolt carrier forces the shoe forward.
• Drop-in installation: No gunsmithing required. The FRT-MR3 fits standard HK MR223 and MR556 lower receivers. Includes all necessary pins and springs. Compatible with mil-spec safety selectors.

Additional specifications: The trigger is constructed from heat-treated steel components with a corrosion-resistant finish. The hammer is designed to work with HK factory bolt carriers. Pull weight is approximately 4.5 to 5.5 pounds in semi-automatic mode. Forced-reset mode pull weight varies based on bolt carrier speed and ammunition. The flat shoe measures 0.500 inches wide with a serrated face.

Who It’s For

This FRT-MR3 (Flat) Single-Stage (3-Position) forced reset trigger for the HK MR223 & HK MR556 is for shooters who understand the mechanical relationship between bolt carrier velocity and trigger reset. It is not for first-time builders or casual plinkers. If you run competition stages where split times matter, or if you train with a focus on recoil management and follow-through, this trigger gives you a repeatable mechanical advantage. The forced-reset function also benefits shooters who want to reduce finger movement during rapid strings. If you own an HK MR223 or MR556 and you have already upgraded the charging handle, buffer system, or barrel, this is the logical next step to get the most out of the platform’s gas system.

Shipping & FFL

This trigger is a firearm component and will ship directly to your door. No FFL transfer is required for this item because it is not a firearm frame or receiver. However, you must be 18 years or older to purchase, and we reserve the right to verify age and compliance with all applicable federal, state, and local laws. Some states and municipalities have restrictions on forced-reset triggers, binary triggers, or devices that increase rate of fire. It is your responsibility to check your local laws before ordering. We ship via UPS Ground or USPS Priority Mail with signature confirmation. Typical delivery time is 3 to 7 business days after order processing. If you have questions about compatibility with specific lower receivers or bolt carrier groups, contact our team before placing your order.