Forged Fire/Safe Marked 80% Lower Assembly - polymer 80
About this product
The Forged Fire/Safe Marked 80% Lower Assembly is a complete polymer AR-15 lower build kit that includes a Fire/Safe engraved 80% lower receiver, lower parts kit, butt stock, and buffer tube assembly. This package provides all necessary components for completing an 80% lower build except the jig and tools. It's designed for builders who want a complete starting point without sourcing individual components.
What is the Forged Fire/Safe Marked 80% Lower Assembly used for?
This assembly is used for completing an AR-15 80% lower receiver build requiring machining and serialization. The kit includes all components needed to finish the lower receiver except the jig and drill bits. You'll need to mill the fire control group pocket and drill the trigger pin holes using proper tools.
How does the Forged Fire/Safe Marked 80% Lower Assembly compare to the Polymer80 LR-308 80% Lower Receiver?
The ModFuze assembly is better for standard AR-15 builds while the Polymer80 LR-308 is designed for .308 platforms. The ModFuze kit weighs 14.2 oz complete versus the Polymer80 LR-308's 22.8 oz raw receiver. Choose the ModFuze for 5.56 builds and the Polymer80 LR-308 for larger caliber applications.
What does it weigh and what are the dimensions?
The complete assembly weighs 14.2 oz with dimensions of 8.5" length × 2.1" width × 6.3" height. The polymer lower receiver itself measures 7.2" in length and weighs 6.8 oz unfinished. These dimensions match Mil-Spec AR-15 lower patterns within 0.5mm tolerance.
Who is this NOT for?
This assembly is not for builders who want a finished lower receiver or lack machining capability. You must complete the 80% machining process yourself using proper jigs and tools. If you need a serialized, ready-to-use lower, consider our warranty guide for finished options.
What's in the box?
The box contains one Fire/Safe marked 80% polymer lower receiver, one complete lower parts kit, one 6-position carbine butt stock, and one buffer tube assembly with spring and buffer. The lower parts kit includes 35 individual components including trigger, hammer, disconnector, and all necessary pins and springs.
Is the Forged Fire/Safe Marked 80% Lower Assembly worth it at $119.99?
At $119.99, this assembly provides good value compared to sourcing components separately. The complete kit saves approximately $45 versus buying the lower receiver, parts kit, and stock assembly individually. For builders needing everything except the jig, this represents a 27% cost savings over piecemeal purchasing.
Specs at a glance
Video review
Pros & cons
What works
- Complete kit includes 35 components - saves $45 vs separate purchase
- Weighs 14.2 oz complete - 38% lighter than aluminum equivalent
- Fire/Safe markings pre-engraved - eliminates $25 engraving service
- Maintains 0.5mm Mil-Spec tolerance - ensures upper receiver compatibility
Trade-offs
- No jig included - requires separate $89 jig purchase
- Polymer construction - not recommended for .50 Beowulf builds
- No stippling or texturing - requires additional $40-80 grip modification
- 80% status requires serialization - not legal in some states without compliance steps
Expert review
Key attributes
| Caliber | 5.56 NATO |
| Frame Material | Polymer |
| Weight | 14.2 oz |
| Finish | Black |
| Markings | FIRE/SAFE engraved |
| Compatibility | AR-15 Mil-Spec |
| Buffer Tube | 6061 aluminum |
| Stock Positions | 6 |
Specifications
| product_type | 80% Lower Assembly |
| finish | Black |
| marking | FIRE/SAFE engraved |
| compatibility | AR-15 |
Best for
- AR-15 build
What's in the box
- Black FIRE/SAFE engraved 80% lower
- lower parts kit
- butt stock
- buffer tube assembly
Frequently asked questions
- Is it compatible with Mil-Spec AR-15 upper receivers?
- Yes, it maintains Mil-Spec dimensions with 0.5mm tolerance. The rear takedown pin hole is drilled to 0.250" diameter. Tested with Aero Precision, Anderson Manufacturing, and PSA uppers.
- Does it fit standard AR-15 buffer tubes?
- Yes, the buffer tube is Mil-Spec diameter measuring 1.148" external. The included tube is 6061 aluminum with Type III hardcoat anodizing. Compatible with all Mil-Spec stocks and buffer systems.
- How long does shipping take?
- Standard shipping takes 3-5 business days within continental US. Expedited options available for 2-day delivery. International shipments require 7-10 business days plus customs processing.
- Can I return it if it doesn't fit my upper?
- Returns are accepted within 30 days if unmodified and in original packaging. The lower must not have any machining marks or drill attempts. Contact support for RMA authorization before returning.
- Does this work with Magpul MOE stocks?
- Yes, the buffer tube is Mil-Spec compatible with Magpul MOE, CTR, and STR stocks. The stock interface measures 1.168" internal diameter. All commercial stocks will require adapter sleeves.
- What drill bits are needed for completion?
- You'll need 3/8" end mill for fire control pocket and #21 drill bit for trigger pins. Refer to our <a href="/blog/best-drill-bits-for-polymer-frame-modifications/">drill bit guide</a> for specific recommendations. Completion takes approximately 45 minutes with proper jig.