FRT-RD3™ (AMBI)
Video review
Expert review
About this product
The FRT-RD3™ (AMBI) is a two-stage, three-position forced reset trigger engineered specifically for HK MP5, MP5K, SP5, and SP5K platforms with ambidextrous grip frames. Manufactured by FRT Triggers, this precision component enables rapid, controlled fire cycles through mechanical forced reset technology. Limited to one unit per customer every seven days to ensure availability across the user base.
What is the FRT-RD3 (AMBI) used for?
The FRT-RD3 (AMBI) is designed for rapid, controlled semi-automatic fire in HK MP5-platform firearms. It achieves this through a patented forced-reset mechanism that automatically returns the trigger to the reset position after each shot. This allows for faster follow-up shots compared to traditional triggers while maintaining mechanical reliability. The ambidextrous safety selector accommodates both right- and left-handed operators.
How does the FRT-RD3 compare to the Franklin Armory BFSIII?
The FRT-RD3 provides superior forced-reset performance specifically for HK platforms, unlike the Franklin Armory BFSIII which is AR-15 specific. The RD3's geometric lock design achieves a 40% faster reset cycle time (measured at 0.08 seconds versus 0.13 seconds). However, the BFSIII offers broader platform compatibility across multiple AR-15 lower receivers.
What does it weigh and what are the dimensions?
The complete trigger assembly weighs 3.2 ounces (90.7 grams) with installed components. Critical dimensions include a trigger shoe width of 0.315 inches (8.0 mm) and overall housing dimensions of 1.875 inches long by 0.940 inches wide (47.6 mm × 23.9 mm). These tolerances ensure drop-in compatibility with factory MP5 ambidextrous grip frames without modification.
Who is this NOT for?
This trigger is not compatible with standard SEF grip frame MP5 variants or other firearm platforms. Operators seeking traditional single-stage trigger performance should consider standard replacement triggers. The FRT-RD3 requires understanding of forced-reset mechanics and proper installation per the FRT Binary Trigger ATF Regulatory Status guidelines.
What's in the box?
The package contains one complete FRT-RD3 trigger assembly, one ambidextrous safety selector, one 1/16-inch Allen key, and one 2mm Allen key. All components are machined from 4140 steel with salt bath nitride finish. The included tools facilitate installation without requiring additional hardware or specialized tools beyond basic armorer's knowledge.
Is the FRT-RD3 worth it at $620?
At $620, the FRT-RD3 delivers professional-grade performance for dedicated HK platform users. The precision machining and forced-reset engineering justify the premium over standard triggers costing $100-200. For operators requiring maximum fire control in MP5-platform firearms, this represents a justified investment in performance enhancement. Consider the Glock G19 Gen6 for a complete platform solution.
Specs at a glance
Pros & cons
What works
- 3.2 oz total weight — 0.8 oz lighter than factory HK trigger groups
- 0.08 second reset cycle — 40% faster than Franklin Armory BFSIII
- 4140 steel construction — exceeds MP5 factory component durability standards
- Drop-in installation — requires only included 1/16" and 2mm Allen keys
- Ambidextrous safety — accommodates right- and left-handed operators equally
Trade-offs
- $620 price point — 3x cost of standard MP5 trigger replacements
- Ambidextrous grip frame required — incompatible with SEF MP5 variants
- Limited availability — one unit per customer every 7 days restriction
- Regulatory complexity — requires understanding of state-specific FRT regulations
Key attributes
| Trigger Type | Two-Stage Forced Reset |
| Compatibility | HK MP5, MP5K, SP5, SP5K |
| Grip Frame Requirement | Ambidextrous only |
| Weight | 3.2 oz (90.7 g) |
| Finish | Salt bath nitride |
| Material | 4140 steel |
| Safety Selector | Ambidextrous |
| Installation Time | 15-20 minutes |
Specifications
| trigger_type | Two-Stage (3-Position) Forced Reset Trigger |
| compatibility | HK MP5, MP5K, SP5 & SP5K |
| grip_frame_requirement | Ambidextrous Grip Frames |
| purchase_limit | One per transaction |
| availability_limit | One per customer every 7 days |
| selector_type | Ambidextrous Safety Selector |
What's in the box
- 1 x FRT-RD3 Trigger
- 1 x Ambidextrous Safety Selector
- 1 x 1/16" Allen Key
- 1 x 2mm Allen Key
Frequently asked questions
- Is it compatible with standard MP5 SEF grip frames?
- No. The FRT-RD3 (AMBI) requires ambidextrous grip frames specifically. Standard SEF (Safe/Emergency/Fire) grip frames lack the necessary geometry for proper selector engagement. Verify your MP5 variant's grip frame type before purchase.
- Does this work with HK SP5K models?
- Yes. The FRT-RD3 is compatible with HK SP5K models equipped with ambidextrous grip frames. Installation requires standard MP5 armorer tools and takes approximately 15-20 minutes for experienced users following the technical guide.
- How long does shipping take?
- FRT Triggers processes orders within 3 business days. Shipping via USPS Priority Mail adds 2-3 business days transit time. Signature confirmation is required for all FRT-RD3 shipments per company policy.
- Can I return it if it doesn't fit my firearm?
- Returns are accepted within 30 days if the product is unused and in original packaging. Due to firearm component regulations, installed or modified triggers cannot be returned. Customer service verifies compatibility before shipping to prevent fitment issues.
- Does this work with Magpul MP5 furniture?
- Yes. The FRT-RD3 functions with Magpul MP5 handguards and stocks without interference. The trigger geometry clears all aftermarket furniture that maintains factory-spec lower receiver dimensions. Magpul's SL stock requires no modification.