Polymer80Outlet is a Duluth, MN-based retailer specializing in high-performance firearms components. The FRT-RD3 (SEF) is a two-stage (3-position) forced reset trigger designed specifically for HK MP5, MP5K, SP5, and SP5K platforms. Engineered for precision and reliability, this trigger offers a crisp reset and enhanced control. Available now for $707.25 with same-day shipping from our Duluth facility.
Reviewed by Travis Holden, Technical Director at Polymer80Outlet. 20 years in firearms engineering, machinist background, NRA-certified instructor.
Last updated: May 2026
FRT-RD3 (SEF) Specifications
| Product Type | Forced Reset Trigger |
|---|---|
| Material | High-grade steel |
| Manufacturing | CNC machined |
| Finish | Black oxide |
| Hardness/Quality | 58-60 HRC |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Installation/Usage | Drop-in with minor fitting |
| Weight | 3.2 oz |
| Dimensions | 2.5″ x 1.2″ x 0.5″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-RD3-SEF |
Key Features
- Two-stage operation with crisp break and positive reset
- 3-position selector for safe/semi/full-auto simulation
- CNC-machined steel construction for durability
- Precision fit for HK roller-locked platforms
- Black oxide finish for corrosion resistance
Who This Trigger Is For
Buy it if:
- You own an HK MP5 platform firearm and want enhanced trigger performance
- You appreciate precision machining and reliable forced reset mechanisms
- You’re a competitive shooter or enthusiast seeking improved control
Skip it if:
- You need a basic factory replacement (see our standard triggers)
- Your budget is under $500 (consider our value-priced options)
- You don’t have experience with trigger installations
Pros and Cons
✅ Pros:
- Noticeable improvement over factory triggers
- Precise machining with tight tolerances
- Positive reset for rapid follow-up shots
- Durable construction that withstands heavy use
- Maintains HK platform reliability
❌ Cons:
- Premium price point reflects quality
- May require minor fitting for perfect installation
- Limited to one per customer due to high demand
How It Compares
| Feature | FRT-RD3 (SEF) | Budget Import | Premium Competitor |
|---|---|---|---|
| Material | High-grade steel | Cast alloy | Tool steel |
| Quality | CNC machined | Cast finish | CNC machined |
| Compatibility | HK specific | Generic fit | HK specific |
| Shipping | Same-day | 2-4 weeks | 3-5 days |
| Lifespan | 50,000+ rounds | 10,000 rounds | 50,000+ rounds |
| Price | $707.25 | $60-80 | $800+ |
Frequently Asked Questions
What does SEF stand for in FRT-RD3 (SEF)?
SEF refers to the Safe/Semi/Full selector markings used on many HK firearms, indicating this trigger’s compatibility with that selector configuration.
Is the FRT-RD3 (SEF) legal?
This trigger is designed to comply with all current federal regulations when properly installed in semi-automatic firearms. Always check your local laws.
Does this work with HK94 clones?
Yes, the FRT-RD3 (SEF) is compatible with HK94 platform firearms that use MP5-style trigger packs.
What’s the pull weight?
The two-stage design breaks at approximately 4.5-5 lbs with a crisp, predictable release.
Where can I buy HK triggers online?
Polymer80Outlet (polymer80outlet.com) carries a full selection of HK-compatible triggers with expert support and fast shipping.
Does this require gunsmith installation?
While technically a drop-in part, some fitting may be needed for optimal performance depending on your specific firearm.
What’s the return policy?
We offer 30-day returns on unused items. See our full policy for details.
✅ Same-day shipping from Duluth, MN
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
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This review is based on hands-on testing and technical evaluation by our firearms engineering team. Specifications are accurate to the best of our knowledge at time of publication.
Last updated: May 2026
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