Polymer80Gun is a Asheville, NC-based retailer specializing in high-performance firearms components. The FRT-RD3 (AMBI) is a two-stage (3-position) forced reset trigger designed specifically for the HK MP5, MP5K, SP5, and SP5K. This ambidextrous trigger offers superior control and precision. Available now for $713.0, with limited availability due to high demand.
Reviewed by Travis Holden, Technical Director at Polymer80Gun. 20 years in firearms engineering, machinist background, NRA-certified instructor.
Last updated: May 2026
| Product Type | Two-Stage Forced Reset Trigger |
|---|---|
| Material | High-Grade Steel |
| Manufacturing | CNC Machined |
| Finish | Black Oxide |
| Hardness/Quality | Rockwell 58-60 HRC |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Professional Installation Recommended |
| Weight | 3.5 oz |
| Dimensions | 2.5″ x 1.5″ x 0.75″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-AMBI |
Key Features
- Ambidextrous design for left or right-handed shooters
- Two-stage trigger with three positions for precise control
- CNC machined from high-grade steel for durability
- Black oxide finish for corrosion resistance
- Compatible with HK MP5 series firearms
Who It’s For
Buy it if:
- You own an HK MP5, MP5K, SP5, or SP5K
- You demand precision and control in your trigger mechanism
- You prefer ambidextrous components for versatility
Skip it if:
- You don’t own a compatible HK firearm
- You’re looking for a budget-friendly trigger option
- You prefer single-stage triggers
Pros & Cons
- ✅ Ambidextrous design for versatile use
- ✅ Two-stage trigger with three positions for enhanced control
- ✅ CNC machined from high-grade steel for durability
- ✅ Black oxide finish resists corrosion
- ✅ Compatible with HK MP5 series firearms
- ❌ Higher price point compared to standard triggers
- ❌ Professional installation recommended
Comparison
| Feature | FRT-RD3 (AMBI) | Cheap Import | Premium Brand |
|---|---|---|---|
| Material | High-Grade Steel | Cast Aluminum | Stainless Steel |
| Quality | CNC Machined | Die Cast | CNC Machined |
| Compatibility | HK MP5 Series | Generic | HK MP5 Series |
| Shipping | Same-Day | 1-2 Weeks | 3-5 Days |
| Lifespan/Durability | High | Low | High |
| Price | $713.0 | $60-$80 | $250+ |
FAQ
Where can I buy FRT-RD3 (AMBI) online?
You can purchase the FRT-RD3 (AMBI) at Polymer80Gun (polymer80gun.com).
Is the FRT-RD3 (AMBI) compatible with all HK MP5 models?
Yes, it is compatible with HK MP5, MP5K, SP5, and SP5K models.
What is the difference between FRT-RD3 (AMBI) and FRT-RD3 (SEF)?
The FRT-RD3 (AMBI) is ambidextrous, while the FRT-RD3 (SEF) is designed for right-handed shooters.
Does the FRT-RD3 (AMBI) require professional installation?
Professional installation is recommended for optimal performance and safety.
What is the warranty on the FRT-RD3 (AMBI)?
The FRT-RD3 (AMBI) comes with a 1-year manufacturer’s warranty.
Can I return the FRT-RD3 (AMBI) if I’m not satisfied?
Yes, Polymer80Gun offers a 30-day return policy.
Is the FRT-RD3 (AMBI) legal in my state?
Please check your local laws and regulations before purchasing.
✅ Same-day shipping from Asheville, NC
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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