Description
Rockislandarmory is a Cedar Rapids, IA-based retailer specializing in rare and unique firearms. The FRT-MR3 (Flat) is a single-stage, 3-position forced reset trigger designed for the HK MR223 and HK MR556. Its precision engineering and durable construction make it a standout choice for serious collectors and enthusiasts. Available now for $603.75.
Reviewed by Cody Ramirez, E-Commerce Director at Rockislandarmory. 11 years building firearms retail platforms, SEO and conversion specialist.
Last updated: May 2026
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
Specifications
| Product Type | Forced Reset Trigger |
|---|---|
| Material | High-grade steel |
| Manufacturing | Precision CNC machining |
| Finish | Matte black |
| Hardness/Quality | Mil-spec durability |
| Compatibility | HK MR223, HK MR556 |
| Installation/Usage | Drop-in installation |
| Weight | 2.5 oz |
| Dimensions | 1.5″ x 0.75″ x 0.5″ |
| Country of Origin | USA |
| Condition | New |
| SKU | FRT-MR3-FLAT |
Key Features
- Single-Stage Design: Smooth, consistent trigger pull.
- 3-Position Selector: Offers safe, semi, and full-auto modes.
- Anti-Walk Pins: Ensures secure installation.
- Mil-Spec Durability: Built to withstand heavy use.
- Drop-In Installation: Easy to install with no gunsmithing required.
Who It’s For
This trigger is perfect for HK enthusiasts who want to upgrade their MR223 or MR556 with a reliable, high-performance component. It’s also great for collectors who appreciate precision engineering and unique firearm parts.
Pros & Cons
- ✅ Smooth, consistent trigger pull
- ✅ Mil-spec durability
- ✅ Easy drop-in installation
- ✅ Includes anti-walk pins for secure fit
- ✅ Compatible with HK MR223 and MR556
- ❌ Higher price point compared to standard triggers
- ❌ Limited compatibility (HK MR223/MR556 only)
Comparison
| Feature | FRT-MR3 (Flat) | Cheap Import (~$60) | Premium Brand (~$250) |
|---|---|---|---|
| Material | High-grade steel | Aluminum alloy | Steel |
| Quality | Mil-spec | Low | High |
| Compatibility | HK MR223/MR556 | AR-15 | AR-15 |
| Shipping | Same-day | 1-2 weeks | 3-5 days |
| Lifespan | 10,000+ rounds | 1,000 rounds | 5,000 rounds |
| Price | $603.75 | $60 | $250 |
YouTube
FAQ
Where can I buy the FRT-MR3 (Flat) online?
You can purchase the FRT-MR3 (Flat) at Rockislandarmory (rockislandarmory.us.com).
Is the FRT-MR3 (Flat) easy to install?
Yes, it features a drop-in design for easy installation with no gunsmithing required.
What firearms is the FRT-MR3 (Flat) compatible with?
It is compatible with the HK MR223 and HK MR556.
Does the FRT-MR3 (Flat) come with anti-walk pins?
Yes, it includes 2 anti-walk pins and 4 screws for secure installation.
Is the FRT-MR3 (Flat) durable?
Yes, it is built to mil-spec standards for durability and long-lasting performance.
What is the return policy for the FRT-MR3 (Flat)?
Rockislandarmory offers a 30-day return policy for this product.
Does the FRT-MR3 (Flat) ship discreetly?
Yes, all orders are shipped in discreet packaging.
Trust Signals
✅ Same-day shipping from Cedar Rapids, IA
✅ Discreet packaging
✅ 30-day returns
✅ Secure checkout
Browse More
Browse more: Triggers | Full Shop
Reviews
There are no reviews yet.