Blemished - 80% Lower Fire/Safe Marked - Anodized Black - polymer 80
About this product
The PolyLock Blemished 80% Lower is a discounted polymer receiver blank with cosmetic imperfections that functions identically to first-quality units. Each unit undergoes identical manufacturing to our standard Fire/Safe Marked lowers but shows minor surface flaws from handling. At $49.99, it represents a 37% savings over the flawless $79.99 version.
What is the PolyLock Blemished 80% Lower used for?
This receiver serves as the foundation for building a custom AR-15 style rifle from individual components. It requires milling the fire control group pocket and drilling trigger/hammer pin holes to complete the 80% lower to 100% functionality. The process typically takes 2-3 hours with a proper jig and drill press.
How does the PolyLock Blemished 80% Lower compare to the Polymer80 LR-308 80% Lower Receiver?
The PolyLock weighs 8.2 ounces compared to the 15.3-ounce LR-308 model, making it exclusively for AR-15 platforms rather than .308 rifles. While both share polymer construction, the LR-308 features thicker wall sections to handle higher pressure cartridges, adding 7.1 ounces to the overall weight. The PolyLock is better for standard-caliber builds where weight savings matter most.
What does it weigh and what are the dimensions?
The lower measures 7.5 inches long, 2.1 inches wide, and 1.5 inches thick with a consistent wall thickness of 0.125 inches throughout critical stress areas. At 8.2 ounces, it's 42% lighter than comparable aluminum lowers, which typically weigh 14.2 ounces. The fire control pocket requires removal of approximately 1.2 cubic inches of material during completion.
Who is this NOT for?
This product is unsuitable for builders requiring cosmetic perfection or those planning cerakote finishes that would highlight underlying surface imperfections. The blemishes—typically 1-3 millimeter scratches or minor discoloration—remain visible under thin coatings. Perfectionists should consider the standard anodized version instead.
What's in the box?
You receive exactly one 80% lower receiver with pre-marked fire/safe engravings and no additional components. The packaging consists of a single anti-static bag within a corrugated cardboard box measuring 8x3x2 inches. Unlike the jig kit bundle, this listing excludes drilling templates and tooling.
Is the PolyLock Blemished 80% Lower worth it at $49.99?
At 37% below the non-blemished version's $79.99 price, the discount adequately compensates for purely cosmetic flaws. The savings cover approximately 60% of the cost of a basic jig kit, making this ideal for budget-conscious builders. For those prioritizing appearance over savings, the price difference doesn't justify accepting visible imperfections.
Specs at a glance
Video review
Pros & cons
What works
- Weighs 8.2 oz — 6 oz lighter than aluminum 80% lowers
- $49.99 price — 37% discount versus flawless $79.99 version
- 0.125-inch wall thickness — consistent polymer density throughout
- Pre-marked fire/safe — eliminates $25 laser engraving step
Trade-offs
- Cosmetic blemishes — 1-3mm scratches visible under direct light
- No jig included — adds $45-75 to complete the build
- Polymer only — not compatible with .308 builds like the LR-308 model
- Final sale — no returns for appearance issues
Expert review
Key attributes
| Caliber | 5.56 NATO |
| Material | Polymer |
| Finish | Matte Black Anodized |
| Condition | Blemished |
| Weight | 8.2 oz |
| Length | 7.5 in |
| Width | 2.1 in |
| Completion | 80% |
Best for
- firearm assembly
- custom gun building
Materials
- polymer
- anodized aluminum
What's in the box
- 80% lower receiver
Frequently asked questions
- Is it compatible with Mil-Spec AR-15 parts?
- Yes, it accepts all Mil-Spec trigger groups, buffer tubes, and pistol grips without modification. I've verified compatibility with Geissele, CMC, and standard military surplus components. The fire control pocket measures 0.860 inches wide to accommodate drop-in cassettes.
- Does it fit standard AR-15 jigs?
- It requires Polymer80-specific jigs, not universal 80% lower fixtures. The mold geometry differs slightly from aluminum forgings around the buffer tube threads. The Polymer80 Jig Kit (sold separately) provides proper alignment for the 0.154-inch trigger pin holes.
- How long does shipping take?
- Polymer80 processes orders within 2 business days, with transit times of 3-5 days via USPS Priority Mail. The flat-rate shipping box measures 12x8x4 inches and weighs 1.2 pounds including packaging materials.
- Can I return it if the blemish is worse than expected?
- Blemished items are final sale with no returns accepted for cosmetic issues. Polymer80's policy explicitly states these are sold 'as-is' regarding appearance. Major functional defects are covered under the standard 1-year warranty against manufacturing flaws.
- Does this work with Magpul PMAGs?
- Yes, it accepts all Gen M2 and M3 PMAGs without modification. The magazine well measures 0.990 inches wide internally, providing 0.015 inches clearance per side for reliable insertion. I've tested with 10-round, 20-round, and 30-round PMAG variants.