FRT-MR3™ Forced Reset Trigger
The FRT-MR3™ brings the patented forced reset trigger experience to the HK MR223 and HK MR556 platform for the first time. A single-stage, 3-position forced reset trigger purpose-built for HK’s MR-series rifles — delivering the same BCG-driven mechanical reset that made the FRT-15 legendary, now engineered precisely for the HK trigger group geometry.
| Model | FRT-MR3™ |
| Type | Single-Stage Forced Reset Trigger |
| Positions | 3 (Safe / Semi-Auto / Forced Reset) |
| Compatible Platforms | HK MR223, HK MR556 |
| Material | Tool-Grade Steel, Precision Machined |
| Finish | Corrosion-Resistant Coating |
| Install | Drop-In, No Modification Required |
| Legal Status | Federally Legal — DOJ Settlement Confirmed |
| Warranty | Manufacturer’s Limited Warranty |
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Product Summary
The FRT-MR3™ brings the patented forced reset trigger experience to the HK MR223 and HK MR556 for the first time. Engineered by Rare Breed Triggers, it delivers three selectable positions — Safe, Semi-Auto, and Forced Reset — in a single drop-in assembly purpose-built for the HK MR-series trigger group geometry.
The patented BCG-driven reset mechanism delivers mechanically faster, more consistent reset than any spring-driven trigger. One round per trigger pull. Federally legal — confirmed by the DOJ settlement with Rare Breed Triggers. No modification required. Ships direct with full warranty coverage.
HK precision. Rare Breed performance. Forced reset — finally.
What Is the FRT-MR3™?
The FRT-MR3™ is the result of Rare Breed Triggers applying its patented forced reset trigger engineering to one of the most respected rifle platforms in the world — the HK MR223 and HK MR556. HK’s MR-series rifles are known for their exceptional build quality, reliability, and the precision of their roller-delayed or piston-driven operating systems. The FRT-MR3™ takes that platform to the next level, delivering the BCG-driven forced reset mechanism that has made the FRT-15 the benchmark for AR-15 trigger performance — now purpose-engineered for the HK MR trigger group.
Developing a forced reset trigger for the HK MR223 and MR556 required platform-specific engineering. The HK MR-series uses a different trigger group geometry and housing than a standard mil-spec AR-15 lower. Rare Breed Triggers’ engineers designed the FRT-MR3™ specifically around the HK MR trigger pack dimensions, ensuring a precise fit and reliable function without requiring any modification to the host rifle.
The result is a three-position forced reset trigger that drops directly into HK MR223 and MR556 rifles and delivers the same revolutionary performance HK shooters have been waiting for. Available exclusively at rare-breedtriggers.com — the only authorized source for genuine Rare Breed FRT products.
Why the HK MR Platform Deserves the FRT-MR3™
The HK MR223 and HK MR556 are among the finest semi-automatic rifles available to civilian shooters in the United States. Their gas-piston operating systems deliver exceptional reliability and reduced fouling compared to direct impingement designs. Their build quality is benchmarked against military specifications. They deserve a trigger that matches that standard — and until the FRT-MR3™, no forced reset trigger existed that could.
According to the National Shooting Sports Foundation, trigger upgrades consistently rank among the most impactful modifications shooters make to their rifles. For HK MR-series owners, the FRT-MR3™ is the definitive trigger upgrade — combining the precision engineering of the HK platform with the patented forced reset performance that only Rare Breed Triggers can deliver. Read more on our blog.
Three Positions. One Trigger.
The FRT-MR3™ gives HK MR223 and MR556 owners three selectable firing modes — all within a single drop-in trigger assembly.
Trigger sear mechanically disconnected. The firearm cannot fire regardless of trigger pressure. Standard safe carry and storage position for all non-firing situations.
Standard single-stage semi-automatic function. One round per deliberate trigger pull. Spring-driven reset. Ideal for precision shooting, deliberate target engagement, and all standard semi-auto applications on the HK MR platform.
The patented BCG-driven reset engages. The bolt carrier group physically drives the trigger forward after each shot — delivering mechanically faster, more consistent reset than any spring-driven system. One round per trigger pull. Federally legal semi-automatic operation.
HK-Specific Precision Engineering
The FRT-MR3™ is not an adapted AR-15 trigger — it is engineered from the ground up for the HK MR-series trigger group geometry. Every dimension is specific to the HK MR223 and MR556 platform for a precise, reliable fit.
The bolt carrier group physically drives the trigger forward during each cycling event — the same patented forced reset mechanism that made the FRT-15 revolutionary, now available for HK MR-series shooters.
All primary wear surfaces precision machined from tool-grade steel. Built to match the durability standard of the HK MR platform itself — thousands of rounds of reliable, consistent service.
The FRT-MR3™ installs directly into HK MR223 and MR556 rifles without modification to the host firearm. No machining, no permanent changes — drop-in and shoot.
One round per trigger pull in every position. Semi-automatic classification confirmed by the landmark DOJ settlement with Rare Breed Triggers. The only forced reset trigger with this level of documented legal standing.
Every FRT-MR3™ purchased directly from Rare Breed Triggers ships with the manufacturer’s limited warranty. Only direct purchases are eligible for warranty coverage.
Federally Legal. DOJ Confirmed.
The FRT-MR3™ carries the same federally confirmed legal status as all Rare Breed Triggers products — documented semi-automatic classification established through the landmark DOJ settlement.
The FRT-MR3™ fires one round per single function of the trigger in every position. Under the National Firearms Act and Gun Control Act, a machine gun fires more than one round per trigger function. The FRT-MR3™ does not meet this definition — confirmed by the DOJ settlement with Rare Breed Triggers.
State laws vary. Always verify your state’s regulations before purchasing. Read our full legal guides on the blog.
Frequently Asked Questions
The FRT-MR3™ is purpose-engineered for the HK MR223 and HK MR556. It is designed specifically around the HK MR-series trigger group geometry and is not compatible with standard mil-spec AR-15 lowers or other HK platforms outside the MR223/MR556 family.
Yes. The FRT-MR3™ is a federally legal semi-automatic trigger — one round per trigger pull in every position. Its legal status is confirmed by the DOJ settlement with Rare Breed Triggers. State laws vary — always verify your state’s regulations before purchasing. Read our legal breakdown here.
No. The FRT-MR3™ is a drop-in trigger assembly designed for the HK MR223 and MR556 trigger group housing. No machining, no permanent modification to your rifle is required. Standard trigger installation tools are all you need.
The only authorized source is rare-breedtriggers.com. Purchasing direct guarantees product authenticity, manufacturer warranty, and legal compliance documentation. There are no authorized third-party resellers.
Both the FRT-MR3™ and the FRT-15 use the same patented BCG-driven forced reset mechanism and three-position selector system. The difference is platform specificity — the FRT-15 is engineered for mil-spec AR-15 lowers, while the FRT-MR3™ is purpose-built for the HK MR223 and HK MR556. The performance experience is equivalent; the engineering is tailored to each platform.
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Order the FRT-MR3™ Today
The forced reset trigger HK MR223 and MR556 owners have been waiting for. Patented. Federally legal. Built by the company that invented the FRT.
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