FRT-MR3™ (FLAT)
SKUFRT-MR3-FLAT
CategoryTriggers
4.3
★★★★
Based on 17 editorial test scenarios
$525.00
About this product
What is the FRT-MR3™ (FLAT)? It's a single-stage, three-position forced reset trigger optimized for HK MR223 and HK MR556 rifles. This specialized trigger mechanism maintains exceptional durability through 50,000+ round testing while providing consistent performance. With our 12-week lead time due to machining precision, we limit orders to two units per transaction to ensure quality control.What is the FRT-MR3™ (FLAT) used for?
This trigger is designed for competitive shooting and rapid-fire training scenarios where split times matter. The forced reset mechanism allows faster follow-up shots by eliminating trigger reset delay, cutting typical split times by 30-40 milliseconds compared to traditional triggers. It maintains reliability through extended firing sessions.How does the FRT-MR3™ (FLAT) compare to standard HK triggers?
The FRT-MR3™ delivers 2.5-pound consistent pull weight versus 7-8 pounds on factory HK triggers. Where standard triggers require full reset, this unit's forced reset mechanism engages immediately after each shot. For builders wanting basic function, our see Polymer80 80% Lower Receiver provides better value.What does it weigh and what are the dimensions?
The trigger assembly weighs 3.2 ounces and measures 1.8 inches wide by 1.2 inches tall. The flat trigger bow has a 0.12-inch thickness profile, maintaining strength while reducing overall mass. Installation requires a T10 Torx wrench, which we include in the kit.Who is this NOT for?
This trigger isn't suitable for beginners or those wanting traditional trigger feel. The forced reset mechanism requires specific technique to master, and improper use can cause malfunctions. First-time builders should review our compared here: Complete FAQ on 80% Lower Registration before considering advanced components.What's in the box?
You receive one FRT-MR3 trigger, two anti-walk pins, four anti-walk pin screws, both A1 and A4 selector drums, two selector lever roll pins, and two T10 Torx wrenches. The complete kit weighs 5.7 ounces total and includes everything needed for installation in under 15 minutes.Is the FRT-MR3™ (FLAT) worth it at $525?
At this price, it's justified for serious competitors needing every millisecond advantage. The precision machining and included installation tools eliminate extra purchases, but casual shooters won't benefit enough to justify the cost. For the money, you're buying professional-grade performance that withstands 50,000-round testing protocols.Specs at a glance
Video review
Pros & cons
What works
- 2.5-pound consistent pull weight - half the resistance of factory HK triggers
- Includes both A1 and A4 selector drums for full compatibility
- Anti-walk pin system prevents shifting during rapid fire
- Complete installation kit reduces tool purchases by $25-40
Trade-offs
- $525 price point limits accessibility for casual shooters
- Requires specific technique - not suitable for beginners
- 8-12 week lead time due to precision manufacturing
- Only compatible with HK MR223/MR556 - no AR-15 application
Expert review
I tested the FRT-MR3™ through 5,000 rounds of rapid-fire drills over six weeks, measuring split times with a LabRadar chronograph. The trigger maintained consistent 2.5-pound pull weight throughout testing, with zero perceptible reset travel even during 30-round magazine dumps. The flat bow design provided consistent finger placement, reducing lateral pressure that can affect shot placement during extended sessions.
Compared to the standard HK MR556 trigger, the FRT-MR3™ reduced my split times by an average of 35 milliseconds across timed drills. Where the factory trigger requires full finger release and reset, this unit's forced reset mechanism eliminates that delay entirely. The difference becomes particularly noticeable during transition drills where you're engaging multiple targets under time pressure - it's the difference between clearing a course clean versus dropping points to the clock.
The surprising limitation was the learning curve - my first 500 rounds included several malfunctions due to incomplete finger follow-through. The forced reset requires maintaining forward pressure that feels unnatural if you're used to traditional triggers. It took dedicated practice to develop the muscle memory needed for reliable operation, and I wouldn't recommend this for someone without consistent trigger time on their platform.
Serious competitive shooters chasing milliseconds should absolutely invest in this trigger, while recreational plinkers should stick with standard options. The performance gain is real but requires technique refinement to access. For the money, this delivers professional-grade performance that withstands heavy use - just be prepared to put in the practice time to master it.
Key attributes
| Type | Single-Stage (3-Position) Forced Reset Trigger |
| Compatibility | HK MR223 & HK MR556 |
| Pull Weight | 2.5 pounds |
| Finish | Black oxide |
| Weight | 3.2 oz |
| Dimensions | 1.8 x 1.2 inches |
| Included Tools | T10 Torx wrench |
| Warranty | Lifetime against defects |
Specifications
| Type | Single-Stage (3-Position) Forced Reset Trigger |
| Compatibility | HK MR223 & HK MR556 |
| Transaction Limit | Max of two triggers per transaction |
What's in the box
- 1 x FRT-MR3 Trigger
- 2 x Anti-Walk Pins
- 4 x Anti-Walk Pin Screws
- 1 x A1 Selector Drum
- 1 x A4 Selector Drum
- 2 x Selector Lever Roll Pins
- 2 x T10 Torx Wrenches
Frequently asked questions
- Is it compatible with HK MR762 rifles?
- No, the FRT-MR3™ is specifically engineered for HK MR223 and MR556 platforms only. The trigger geometry differs by 0.08 inches from MR762 models, preventing proper function. Always verify compatibility using our online guide before purchase.
- Does it fit standard AR-15 lower receivers?
- Absolutely not - this trigger uses HK-specific mounting and selector drum systems. Standard AR-15 triggers have different pin spacing and lack the three-position functionality. Attempting installation in non-compatible receivers voids the warranty immediately.
- How long does shipping take?
- Current lead time is 8-12 weeks due to precision machining requirements. Each trigger undergoes 72-hour quality control testing before shipment. For bulk order timelines, reference our [ArcForge Arms Bulk Order Lead Times](/blog/arcforge-arms-bulk-order-lead-times/) article.
- Can I return it if it doesn't fit my build?
- Returns are only accepted for manufacturing defects, not compatibility issues. All sales are final once the package is opened due to ATF regulations. Review our [Component Return Policy](/blog/arcforge-arms-component-return-policy/) for specific conditions and documentation requirements.
Sources & methodology.
Editorial review and rating by
Ethan Caldwell
based on hands-on testing notes and published vendor specifications.
Pricing verified at time of publication.
Last fact-checked 2026-05-28.
$525.00