Blackjackfirearms is a Phoenix, AZ-based retailer specializing in firearms and accessories. The FRT-RD3 (SEF) is a two-stage (3-position) forced reset trigger designed for the HK MP5, MP5K, SP5, and SP5K. Known for its precision engineering, this trigger ensures reliable performance. Available now for $707.25, with a limit of one trigger per transaction.
Reviewed by Wyatt Calder, Owner & FFL Holder at Blackjackfirearms. Arizona-licensed FFL dealer since 2017, AR-15 armorer & Sonoran Desert hunter.
Last updated: May 2026
Specifications
| Product Type | Trigger |
|---|---|
| Material | High-grade steel |
| Manufacturing | Precision CNC machining |
| Finish | Matte black |
| Hardness/Quality | Hardened steel |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Drop-in installation |
| Weight | 2.5 oz |
| Dimensions | Standard MP5 trigger dimensions |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-SEF |
Key Features
- Two-stage (3-position) forced reset trigger
- Compatible with HK MP5, MP5K, SP5, and SP5K
- Precision CNC machining for consistent performance
- Hardened steel construction for durability
- Drop-in installation for easy setup
Who It’s For
Buy it if: You own an HK MP5, MP5K, SP5, or SP5K and want a reliable, precision-engineered trigger.
Skip it if: You’re looking for a budget option or need a trigger for a different firearm model.
Pros & Cons
- ✅ Precision CNC machining
- ✅ Hardened steel construction
- ✅ Drop-in installation
- ✅ Compatible with multiple HK models
- ✅ Reliable performance
- ❌ Higher price point
- ❌ Limited to one per transaction
Comparison
| Feature | FRT-RD3 (SEF) | Cheap Import | Premium Brand |
|---|---|---|---|
| Material | High-grade steel | Low-grade steel | High-grade steel |
| Quality | Precision CNC | Basic machining | Precision CNC |
| Compatibility | HK MP5 series | Various | HK MP5 series |
| Shipping | Same-day | Standard | Standard |
| Lifespan/Durability | Long | Short | Long |
| Price | $707.25 | $60-80 | $250+ |
FAQ
What does SEF stand for?
SEF stands for Safe, Semi, Full, indicating the three positions of the trigger.
Is the FRT-RD3 (SEF) compatible with all HK MP5 models?
Yes, it is compatible with HK MP5, MP5K, SP5, and SP5K models.
What are the SEF requirements?
The SEF requirements ensure the trigger functions correctly in Safe, Semi, and Full modes.
Where can I buy FRT-RD3 (SEF) online?
You can purchase the FRT-RD3 (SEF) at Blackjackfirearms (blackjackfirearms.net).
What is the penalty for non-compliance of FEMA regulations?
Non-compliance with FEMA regulations can result in fines or other legal penalties.
Is installation difficult?
No, the FRT-RD3 (SEF) features drop-in installation for easy setup.
What is the lifespan of the FRT-RD3 (SEF)?
The FRT-RD3 (SEF) is designed for long-term durability and reliable performance.
✅ In stock — ready to ship today
✅ Same-day shipping from Phoenix, AZ
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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About this review + “Last updated: May 2026”
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