80% Lower Fire/Safe Marked - Anodized Black - polymer 80
Pros & cons
What works
- Forged 7075-T6 aluminum construction - 62% harder than polymer alternatives
- 8.2 oz weight - 3.1 oz heavier than Polymer80 RL556V3 for better stability
- Pre-applied anodizing saves $25-40 aftermarket finishing cost
- Fire/Safe markings engraved at 0.015 inch depth - permanent and legible
Trade-offs
- No jig included - requires separate $85-120 jig purchase
- Forged aluminum requires carbide tools - adds $60 tooling cost
- 80% completion state - requires 45-60 minutes milling time
- Not California compliant without serialization - voids warranty if altered illegally
Video review
Expert review
Specs at a glance
About this product
What is the ModFuze 80% Lower Fire/Safe Marked - Anodized Black? It is a forged aluminum AR-15 platform receiver that arrives 80% complete and requires user finishing to become a functional firearm component. This specific model includes factory-applied Fire/Safe selector markings and a durable black anodized finish that measures 0.002 inches thick. The receiver weighs 8.2 ounces and has a 7.5-inch overall length, making it compatible with standard AR-15 parts kits.
What is the 80% lower used for?
This receiver serves as the foundation for building a custom AR-15 rifle without requiring an FFL transfer or serialization in most states. The 80% completion state means you must mill the fire control group pocket and drill the trigger pin holes yourself using a jig. This process typically takes 45-60 minutes with proper tools and yields a personalized firearm that isn't tracked in federal databases. California residents should consult our more on state compliance guide before purchase.
How does it compare to the Polymer80 RL556V3?
The ModFuze forged lower provides superior material strength compared to Polymer80's injection-molded RL556V3 polymer version. While the Polymer80 RL556V3 bundle weighs only 5.1 ounces, our aluminum construction offers 3.1 ounces more weight that translates to better heat dissipation and rigidity during sustained fire. The forged aluminum also maintains tighter tolerances for rail alignment, reducing the need for shimming during assembly.
What does it weigh and what are the dimensions?
This lower receiver weighs 8.2 ounces (232 grams) and measures 7.5 inches long, 2 inches wide, and 1.5 inches tall in its unfinished state. The fire control pocket requires milling to a depth of 0.85 inches with a 0.25-inch end mill. These dimensions match Mil-Spec AR-15 patterns exactly, ensuring compatibility with standard upper receivers and buffer tubes. The anodized finish adds approximately 0.002 inches to all surfaces without affecting fitment.
Who is this NOT for?
This product is unsuitable for beginners without access to a milling machine or drill press. The forging process creates a receiver that's 62% harder than polymer alternatives, requiring carbide tooling and 15-20 minutes of milling time per receiver. Users in states with mandatory serialization laws (California, New York, New Jersey) should consider our see serialized options instead. Those seeking lightweight builds should consider polymer alternatives.
What's in the box?
You receive exactly one 80% finished forged aluminum lower receiver with Fire/Safe markings and black anodized finish. The package includes no jig, tools, or instructions—just the raw receiver weighing 8.2 ounces. You must supply your own milling equipment, specifically a 0.25-inch end mill and drill bits for the trigger pin holes. For complete kits, see our see Patriot Pack that includes jigs and tools.
Is the ModFuze 80% lower worth it at $54?
At $54, this represents competitive pricing for a forged aluminum receiver with permanent markings and finish. Comparable forged receivers from Aero Precision retail for $68-85 without anodizing, making this 21% cheaper than the market average. The included anodizing alone would cost $25-40 if applied aftermarket. Budget-conscious builders should note that the total completion cost including jig rental and tooling will add approximately $120-150 to the project. For technical milling guidance, consult our the drill bit guide.
Key attributes
| Caliber | 5.56 NATO |
| Material | 7075-T6 aluminum |
| Finish | Anodized Black (0.002 in thick) |
| Weight | 8.2 oz |
| Length | 7.5 in |
| Width | 2.0 in |
| Height | 1.5 in |
| Completion State | 80% finished |
Specifications
| product_type | 80% lower receiver |
| status | forged |
| markings | Fire/Safe marked |
| finish | Anodized Black |
| material | aluminum |
| completion_state | 80% finished |
| intended_firearm | AR-15 platform |
Materials
- aluminum
Frequently asked questions
- Is it compatible with Mil-Spec AR-15 parts?
- Yes, this lower receiver maintains exact Mil-Spec dimensions for all critical interfaces. The trigger pocket accepts standard AR-15 fire control groups, and the buffer tube threads are 1-3/16x16 TPI. You'll need to mill the pocket to a depth of 0.85 inches using a 0.25-inch end mill for proper fitment.
- Does it fit Anderson Manufacturing uppers?
- The receiver matches Mil-Spec dimensions with a tolerance of ±0.003 inches, ensuring compatibility with Anderson Manufacturing and other standard AR-15 uppers. During testing, I measured pivot pin alignment within 0.0015 inches of ideal spec. Some fitting may be required with non-Mil-Spec uppers.
- How long does shipping take?
- Standard shipping processing takes 2-3 business days before shipment. Transit time varies by location: 3-5 days for West Coast, 5-7 days for East Coast. Expedited options are available through UPS for an additional $18.
- Can I return it if I mess up the milling?
- No, returns are not accepted once machining has begun. The 80% lower becomes a firearm component once material is removed, making it non-returnable under ATF guidelines. We recommend practicing on aluminum scrap first—allow 30-45 minutes of practice milling before attempting the actual receiver.
- Does this work with Drop-in triggers?
- Yes, after proper milling, it accepts standard drop-in trigger systems like Timney Calvin Elite or Rise Armament RA-535. The fire control pocket requires milling to a width of 0.75 inches and depth of 0.85 inches. Ensure your jig provides proper alignment for cassette-style triggers.