Polymer80Gun is a Asheville, NC-based retailer specializing in high-performance firearms components. The FRT-MR3 (Flat) is a single-stage, 3-position forced reset trigger designed specifically for the HK MR223 and HK MR556 platforms. Engineered for precision and reliability, this trigger offers a superior shooting experience. Available now for $603.75.
Reviewed by Travis Holden, Technical Director at Polymer80Gun. 20 years in firearms engineering, machinist background, NRA-certified instructor.
Last updated: May 2026
| Product Type | Single-Stage Forced Reset Trigger |
|---|---|
| Material | High-Strength Steel |
| Manufacturing | CNC Machined |
| Finish | Black Oxide |
| Hardness/Quality | 58-60 HRC |
| Compatibility | HK MR223, HK MR556 |
| Installation/Usage | Drop-In Installation |
| Weight | 2.5 oz |
| Dimensions | 2.75″ x 1.5″ x 0.5″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-MR3-FLAT |
Key Features
- Single-stage trigger with 3-position forced reset
- Includes anti-walk pins and screws for secure installation
- Comes with A1 and A4 selector drums for versatility
- High-strength steel construction for durability
- CNC machined for precise fit and function
Who It’s For
Buy it if:
- You own an HK MR223 or HK MR556 and want a high-performance trigger
- You prioritize precision and reliability in your firearms components
- You prefer drop-in installation for ease of use
Skip it if:
- You are looking for a budget-friendly option (check our Triggers section for alternatives)
- Your firearm is not compatible with the HK MR223 or HK MR556 platforms
Pros & Cons
- ✅ High-strength steel construction ensures durability
- ✅ CNC machined for precise fit and function
- ✅ Includes anti-walk pins and screws for secure installation
- ✅ Comes with A1 and A4 selector drums for versatility
- ✅ Drop-in installation for ease of use
- ❌ Higher price point compared to budget options
- ❌ Limited compatibility to HK MR223 and HK MR556 platforms
Comparison
| Feature | FRT-MR3 (Flat) | Competitor A | Competitor B |
|---|---|---|---|
| Material | High-Strength Steel | Aluminum Alloy | Stainless Steel |
| Quality | CNC Machined | Cast | CNC Machined |
| Compatibility | HK MR223, HK MR556 | AR-15 | AR-15 |
| Shipping | Same-Day | 3-5 Days | 2-3 Days |
| Lifespan/Durability | High | Medium | High |
| Price | $603.75 | $80 | $250 |
FAQ
Where can I buy the FRT-MR3 (Flat) online?
You can purchase the FRT-MR3 (Flat) at Polymer80Gun.
Is the FRT-MR3 (Flat) compatible with other HK models?
No, the FRT-MR3 (Flat) is specifically designed for the HK MR223 and HK MR556 platforms.
What is included in the package?
The package includes the FRT-MR3 trigger, 2 anti-walk pins, 4 anti-walk pin screws, 1 A1 selector drum, and 1 A4 selector drum.
Is installation difficult?
No, the FRT-MR3 (Flat) is designed for drop-in installation, making it easy to install.
What is the material used in the FRT-MR3 (Flat)?
The FRT-MR3 (Flat) is made from high-strength steel for durability and reliability.
Can I return the product if I’m not satisfied?
Yes, Polymer80Gun offers a 30-day return policy for the FRT-MR3 (Flat).
Is the FRT-MR3 (Flat) legal in all states?
Please check your local laws and regulations before purchasing the FRT-MR3 (Flat).
✅ In stock — ready to ship today
✅ Same-day shipping from Asheville, NC
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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About this review + “Last updated: May 2026”
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