Polymer80Gun is a Asheville, NC-based retailer specializing in firearms components and accessories. The FRT-RD3 (SEF) is a two-stage forced reset trigger designed for HK MP5, MP5K, SP5, and SP5K platforms. Its unique three-position functionality offers enhanced control and precision. Available now for $707.25, with a limit of one trigger per transaction.
Reviewed by Travis Holden, Technical Director at Polymer80Gun. 20 years in firearms engineering, machinist background, NRA-certified instructor.
Last updated: May 2026
| Product Type | Forced Reset Trigger |
|---|---|
| Material | High-Grade Steel |
| Manufacturing | CNC Machined |
| Finish | Phosphate Coated |
| Hardness/Quality | 58-60 HRC |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Drop-In |
| Weight | 2.8 oz |
| Dimensions | 1.5″ x 0.5″ x 0.25″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-SEF |
Key Features
- Two-stage forced reset mechanism
- Three-position selector functionality
- Compatible with HK MP5 series platforms
- CNC machined from high-grade steel
- Phosphate coating for durability
Who It’s For
This trigger is ideal for serious firearms enthusiasts who demand precision and reliability from their HK MP5 series platforms. It’s particularly suited for those who appreciate the tactile feedback and control offered by a two-stage forced reset mechanism.
Pros & Cons
- ✅ Enhanced control with two-stage reset
- ✅ Three-position selector for versatility
- ✅ CNC machined for precision
- ✅ Phosphate coating for durability
- ✅ Made in the USA
- ❌ Higher price point compared to standard triggers
- ❌ Limited to one per transaction
Comparison
| Feature | FRT-RD3 (SEF) | Cheap Import | Premium Brand |
|---|---|---|---|
| Material | High-Grade Steel | Mild Steel | High-Grade Steel |
| Quality | CNC Machined | Cast | CNC Machined |
| Compatibility | HK MP5 Series | Generic | HK MP5 Series |
| Shipping | Same-Day | 1-2 Weeks | 1-2 Weeks |
| Lifespan/Durability | High | Low | High |
| Price | $707.25 | $60-80 | $250+ |
FAQ
Where can I buy the FRT-RD3 (SEF) online?
You can purchase the FRT-RD3 (SEF) at Polymer80Gun (polymer80gun.com).
What does SEF stand for?
SEF stands for Safe, Semi, and Full, indicating the three positions of the selector switch.
What are the SEF requirements?
The SEF requires compatibility with HK MP5 series platforms and proper installation for function.
What is the penalty for non-compliance of FEMA regulations?
Non-compliance can result in fines or other penalties, depending on the specific regulation violated.
Is this trigger easy to install?
Yes, the FRT-RD3 (SEF) is designed for drop-in installation, making it straightforward for most users.
What is the lifespan of this trigger?
With proper maintenance, the FRT-RD3 (SEF) offers a high lifespan due to its CNC machined construction and phosphate coating.
Can I buy more than one trigger?
No, there is a limit of one trigger per transaction for the FRT-RD3 (SEF) model.
✅ Same-day shipping from Asheville, NC
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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