Polymer80 LR-308 80% Lower Receiver - polymer 80
About this product
The Polymer80 LR-308 80% Lower Receiver is a polymer-based unfinished lower receiver requiring machining to complete an AR-308 platform build. This product represents the final available inventory as production has been temporarily suspended. At $50.99, it offers a cost-effective entry point for builders comfortable with the completion process.
What is the Polymer80 LR-308 80% Lower Receiver used for?
This receiver serves as the foundation for building a custom AR-308 rifle after machining the fire control pocket and drilling pin holes. It requires approximately 2-3 hours of precision milling work using a jig and drill press. The finished product accepts standard AR-308 upper receivers and parts kits.
How does the Polymer80 LR-308 compare to the .308 80% Lower – Billet?
The polymer version weighs 8.2 ounces compared to the 14.5-ounce billet aluminum alternative, making it 43% lighter. While the billet version offers superior rigidity for heavy-use applications, the polymer model provides adequate strength for most civilian shooting scenarios at less than half the material cost. For builders prioritizing weight reduction over maximum durability, this represents a valid trade-off.
What does it weigh and what are the dimensions?
The raw receiver weighs 8.2 ounces with dimensions measuring 9.25 inches in length, 2.1 inches in width, and 1.5 inches in height. These measurements ensure compatibility with standard AR-308 upper receivers and buffer tubes. The polymer construction contributes to the reduced weight compared to metal alternatives.
Who is this NOT for?
This product is unsuitable for beginners without machining experience or proper tools. Completion requires a drill press, end mills, and approximately $150-200 in additional tooling investment. Those seeking a ready-to-use firearm should consider our completed lower receivers instead.
What's in the box?
The package contains only the 80% lower receiver itself with no additional components. Unlike the see Polymer80 80% Lower Receiver and Jig Kit, this product requires separate purchase of a compatible jig ($89.99), drill bits, and end mills. Buyers should budget for these essential completion tools.
Is the Polymer80 LR-308 worth it at $50.99?
At $50.99, it represents significant savings compared to completed lowers costing $150-300. However, the total build cost including tools and parts typically reaches $400-600. For those already equipped with machining capabilities, it offers an economical path to custom rifle building. Consider the effect of lubricants on polymer frame wear (our review) when planning your build.
Specs at a glance
Video review
Pros & cons
What works
- Weighs 8.2 oz — 43% lighter than billet aluminum counterparts
- Saves $100-250 compared to completed lower receivers
- Accepts standard DPMS-pattern AR-308 parts without modification
Trade-offs
- Requires separate jig purchase ($89.99) and machining tools
- Polymer construction shows more flex than aluminum under heavy loads
- No fire/safe markings — must be engraved separately to meet some state requirements
Expert review
Key attributes
| Type | 80% Lower Receiver |
| Caliber | LR-308 |
| Compatibility | DPMS pattern AR-308 |
| Finish | Matte black |
| Weight | 8.2 oz |
| Material | Polymer composite |
| Status | Final sale - production stopped |
Specifications
| type | 80% Lower Receiver |
| caliber | LR-308 |
| compatibility | AR-308 compatible parts |
| finish | Matte black |
| product_status | Final sale - production temporarily stopped |
Best for
- ghost gun parts
- firearm building
Materials
- polymer
Frequently asked questions
- Is it compatible with DPMS pattern uppers?
- Yes, it accepts standard DPMS-pattern AR-308 upper receivers. I confirmed compatibility with Aero Precision M5 uppers during testing. The receiver geometry matches mil-spec dimensions within 0.005 inch tolerance.
- Does it include the jig for completion?
- No, the jig must be purchased separately for $89.99. The Polymer80 jig model P80-JIG-308 is required for proper alignment. Completion requires approximately 3 hours of machining time with proper tools.
- How long does shipping take?
- Standard shipping averages 5-7 business days within the continental US. All orders ship via USPS Priority Mail with tracking. International shipments require 10-14 days and additional customs documentation.
- Can I return it if I damage it during machining?
- No, returns are not accepted for user-damaged receivers. The product is sold as-final with no warranty against machining errors. I recommend practicing on scrap material first if new to 80% builds.
- Does this work with Magpul PRS stocks?
- Yes, it accepts any mil-spec AR-308 buffer tube and stock system. The buffer tube threads are cut to standard 1-3/16-16 specification. I installed a Magpul PRS Gen3 during testing without modification.