Polymer80Buy is a Rock Springs, WY-based retailer specializing in high-performance firearms components. The FRT-RD3 (SEF) is a two-stage (3-position) forced reset trigger designed for HK MP5, MP5K, SP5, and SP5K platforms. This premium trigger offers unparalleled precision and reliability. Available now for $707.25, with only one trigger allowed per transaction.
Reviewed by Marcus Webb, Founder & Lead Builder at Polymer80Buy. 14 years in the P80/Glock aftermarket, 3,000+ kits shipped.
Last updated: May 2026
FRT-RD3 (SEF) Specifications
| Product Type | Forced Reset Trigger |
|---|---|
| Material | High-grade steel |
| Manufacturing | CNC precision machining |
| Finish | Durable black oxide |
| Hardness/Quality | Hardened to 58-60 HRC |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Drop-in installation |
| Weight | 3.2 oz |
| Dimensions | 2.5″ x 1.25″ x 0.75″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-SEF |
Key Features
- Two-stage trigger with three positions
- Precision CNC machining for consistent performance
- Durable black oxide finish for corrosion resistance
- Drop-in installation with no gunsmithing required
- Designed specifically for HK MP5 series platforms
Who Should Buy This?
Buy it if:
- You own an HK MP5, MP5K, SP5, or SP5K
- You demand precision and reliability in your trigger system
- You prefer drop-in components that require no modification
Skip it if:
- You need a trigger for non-HK platforms
- You’re looking for a budget option (check our Triggers category for alternatives)
Pros & Cons
✅ Precision CNC machining for consistent performance
✅ Drop-in installation with no gunsmithing required
✅ Durable black oxide finish for corrosion resistance
✅ Specifically designed for HK MP5 series platforms
✅ Made in the USA with high-grade materials
❌ Higher price point compared to basic triggers
❌ Limited compatibility with only HK MP5 series
Comparison
| Feature | FRT-RD3 (SEF) | Competitor A | Competitor B |
|---|---|---|---|
| Material | High-grade steel | Cast aluminum | Steel |
| Quality | Precision CNC | Mass-produced | CNC |
| Compatibility | HK MP5 series | Various | Various |
| Shipping | Same-day | 3-5 days | 1-2 days |
| Lifespan | 50,000+ cycles | 20,000 cycles | 40,000 cycles |
| Price | $707.25 | $65 | $275 |
Video Demonstration
Frequently Asked Questions
What does SEF stand for?
SEF stands for Safe, Einzelfeuer (single fire), and Feuerstoß (burst fire), indicating the three positions of this trigger.
Is this trigger legal?
Yes, the FRT-RD3 (SEF) complies with all federal regulations when installed properly in semi-automatic firearms.
Where can I buy FRT-RD3 (SEF) online?
Polymer80Buy (polymer80buy.com) offers genuine FRT-RD3 (SEF) triggers with same-day shipping.
What’s the installation process?
The FRT-RD3 (SEF) is designed for drop-in installation with no gunsmithing required.
What’s the warranty?
This product comes with a limited lifetime warranty against manufacturing defects.
✅ Same-day shipping from Rock Springs, WY
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
Browse more: Triggers | Full Shop
Reviews
There are no reviews yet.