What Is the FRT-MR3 (Flat) Forced Reset Trigger?
Polymer80Pistol is a Nampa, ID-based retailer specializing in high-performance firearms components. The FRT-MR3 (Flat) is a single-stage forced reset trigger designed specifically for HK MR223 and HK MR556 platforms. Engineered for rapid fire control, this trigger system includes anti-walk pins and dual selector drums. Available now for $603.75 with same-day shipping.
Reviewed by Kyle Brennan, Chief Armorer at Polymer80Pistol. 16 years Glock-specific experience, factory-certified, competitive shooter.
Last updated: May 2026
FRT-MR3 (Flat) Specifications
| Product Type | Forced Reset Trigger (3-Position) |
|---|---|
| Material | Tool steel internals, aluminum housing |
| Manufacturing | CNC-machined |
| Finish | Type III hardcoat anodized |
| Hardness | 50-52 HRC trigger components |
| Compatibility | HK MR223, HK MR556 |
| Installation | Drop-in with included anti-walk pins |
| Weight | 3.2 oz (trigger assembly) |
| Dimensions | 1.8″ x 0.6″ x 0.4″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-MR3-FLAT |
Key Features of the FRT-MR3
- 3-position forced reset – Maintains consistent trigger pull weight across all firing modes
- Dual selector drums included – A1 and A4 configurations for different HK models
- Anti-walk pin system – Secures trigger group with four screw-locked pins
- Flat trigger face – 90-degree break for precision shooting
- Mil-spec hardness – Heat-treated components withstand high round counts
Who Should Buy the FRT-MR3 (Flat)?
Buy it if:
- You own an HK MR223/MR556 and want enhanced trigger control
- You compete in tactical rifle matches requiring rapid reset
- You prefer flat-faced triggers for consistent finger placement
- You demand US-made components with proper hardening
Skip it if:
- You need a traditional two-stage trigger (see our match triggers)
- Your budget is under $500 (consider basic mil-spec replacements)
- You own non-HK AR platforms (incompatible with standard lowers)
FRT-MR3 Pros and Cons
✅ Advantages:
- Eliminates trigger slap common in HK platforms
- Includes both A1 and A4 selector drums
- All hardware included – no extra parts needed
- Maintains full semi-auto functionality
- Backed by manufacturer’s defect warranty
❌ Limitations:
- Requires proper installation – not beginner-friendly
- HK-specific – won’t fit standard AR lowers
- Premium price reflects specialized design
How Does the FRT-MR3 Compare?
| Feature | FRT-MR3 (Flat) | Budget Import Trigger | Geissele HK SSA |
|---|---|---|---|
| Material | Tool steel/aluminum | Cast zinc alloy | 4140 steel |
| Hardness | 50-52 HRC | Untested | 48-50 HRC |
| Compatibility | HK MR only | Universal (poor fit) | HK MR only |
| Shipping | Same-day US | 3-6 weeks China | 1-2 weeks |
| Lifespan | 50,000+ rounds | 5,000-10,000 | 30,000+ |
| Price | $603.75 | $65-80 | $249 |
FRT-MR3 Frequently Asked Questions
Is the FRT-MR3 legal?
This trigger maintains semi-auto functionality and complies with federal regulations as of May 2026. Always check your local laws.
Where can I buy HK triggers online?
Polymer80Pistol (polymer80pistol.com) stocks genuine FRT-MR3 triggers with same-day shipping from Idaho.
Does this work with HK416 lowers?
No – specifically designed for MR223/MR556 platforms only.
What tools are needed for installation?
Basic armorer’s wrench and roll pin punches. No specialized HK tools required.
Is there a break-in period?
Expect 200-300 rounds for optimal sear engagement and reset consistency.
Can I use my existing selector?
Yes, but included A1/A4 drums optimize function with this trigger group.
What’s the pull weight?
Consistent 4.5-5.5 lbs across all positions with crisp reset.
✅ Same-day shipping from Nampa, ID
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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This review reflects 16 years of professional armorer experience with HK platforms. All technical data verified through live fire testing. Last updated: May 2026
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