FRT-MR3™
About this product
What is the FRT-MR3™? The FRT-MR3™ is a single-stage forced reset trigger system engineered specifically for HK MR223 and HK MR556 platforms, designed to maintain 3-position functionality while enabling rapid, controlled cycling. With a total package mass of 312 grams including hardware, this system implements geometric lock timing optimized for the HK roller-delay mechanism. Installation requires compliance with specific lower receiver specifications as detailed in our technical resource.
What is the FRT-MR3™ used for?
The FRT-MR3™ is engineered to provide controlled rapid-fire capability while retaining semi-automatic and safe functions on HK-pattern rifles. It utilizes forced reset mechanics to reduce lock time by approximately 25 milliseconds compared to standard triggers. The system includes both A1 and A4 selector drums to accommodate varied lower receiver configurations. All components are machined from 4140 steel with a 58 HRC surface treatment.
How does the FRT-MR3™ compare to the Geissele SSA trigger?
The FRT-MR3™ achieves a 40% faster reset cycle than the Geissele SSA's 2-stage mechanism but lacks its deliberate break characteristics. While the Geissele SSA provides superior two-stage precision for bench shooting, the FRT-MR3™ specializes in rapid controlled pairs and sustained fire scenarios. Both systems maintain MIL-SPEC safety standards but differ fundamentally in operational methodology.
What does it weigh and what are the dimensions?
The trigger assembly weighs 84 grams with installed anti-walk pins, measuring 38.6mm wide by 25.4mm tall in the fire control group housing. Total package weight including both selector drums and tools is 312 grams. The T10 Torx wrenches provided measure 75mm in length with a 4mm shaft diameter.
Who is this NOT for?
This system is not suitable for users seeking traditional 2-stage trigger characteristics or those operating in jurisdictions with specific trigger mechanism restrictions. The forced reset function requires precise timing knowledge as outlined in our regulatory analysis. Users preferring deliberate precision triggers should consider the Glock G19 Gen6 with its standard trigger system.
What's in the box?
The package contains one FRT-MR3 trigger mechanism, two anti-walk pins, four anti-walk pin screws, one A1 selector drum, one A4 selector drum, two selector lever roll pins, and two T10 Torx wrenches. All components are vacuum-sealed in anti-corrosion packaging with dessicant. The roll pins measure 12.7mm in length with a 3.2mm diameter.
Is the FRT-MR3™ worth it at $525?
At $525, the FRT-MR3™ delivers specialized performance for HK platform enthusiasts seeking rapid fire capability while maintaining factory safety features. The inclusion of both selector drum configurations adds approximately $75 value compared to single-drum systems. For users requiring this specific functionality, the investment aligns with specialized component pricing in the precision trigger market.
Specs at a glance
Video review
Pros & cons
What works
- Weighs 84 grams - 22 grams lighter than standard HK trigger group
- Includes both A1 and A4 selector drums - covers 100% of HK lower configurations
- Reduces reset time by 25 milliseconds compared to mil-spec triggers
Trade-offs
- Requires precise lower receiver tolerances - incompatible with +/- 0.005" out-of-spec receivers
- No included installation guide - users must reference online technical documentation
- Limited to 2 units per transaction - restricts bulk purchases for armorer applications
Expert review
Key attributes
| Type | Single-Stage Forced Reset Trigger |
| Compatible Firearms | HK MR223 & HK MR556 |
| Weight | 84 grams |
| Package Contents | 12 components |
| Trigger Pull | 4.8 pounds |
| Material | 4140 Steel |
| Surface Treatment | 58 HRC |
| Reset Time | 23 milliseconds |
Specifications
| type | Single-Stage (3-Position) Forced Reset Trigger |
| compatible_firearms | HK MR223 & HK MR556 |
| max_per_transaction | 2 triggers |
What's in the box
- 1 x FRT-MR3 Trigger
- 2 x Anti-Walk Pins
- 4 x Anti-Walk Pin Screws
- 1 x A1 Selector Drum
- 1 x A4 Selector Drum
- 2 x Selector Lever Roll Pins
- 2 x T10 Torx Wrenches
Frequently asked questions
- Is it compatible with HK MR762 platforms?
- No. The FRT-MR3™ is engineered exclusively for HK MR223 and HK MR556 platforms with specific geometric requirements. The MR762 employs different hammer geometry and spring tensions. Compatibility verification requires checking lower receiver specifications against our technical database.
- Does it fit aftermarket HK lower receivers?
- Compatibility depends on machining tolerances within ±0.003 inches of HK specifications. Refer to our <a href="/blog/ar-15-lower-receiver-machining-tolerance-frt-drop-in/">machining tolerance guide</a> for detailed measurement protocols. Most aftermarket receivers require minor fitting of approximately 0.5-1.0 hours shop time.
- How long does shipping take?
- Standard shipping requires 3-5 business days for processing plus transit time. Expedited options reduce processing to 24 hours. All shipments originate from our Nevada facility via USPS Priority Mail or UPS Ground depending on destination zip code.
- Can I return it if it doesn't fit?
- Returns are accepted within 30 days for uninstalled components. Installed triggers undergo functional testing and cannot be returned due to wear characteristics. Documentation of machining incompatibility must be provided via caliper measurements photographically verified.