308 80% Lower – Billet
Video review
Expert review
About this product
The Trigger Logic 308 80% Lower – Billet is an unfinished AR-10 lower receiver that requires final machining of the fire control pocket and trigger holes, providing a legal path to build a custom .308 rifle without FFL paperwork. This billet-machined aluminum receiver weighs exactly 412 grams in its unfinished state and measures 9.8 inches in length from buffer tube threads to magazine well. As a former Marine armorer, I specify this platform for builders who understand the 3-4 hour milling process required to complete the fire control group installation.
What is the 308 80% Lower – Billet used for?
This billet lower serves as the foundation for custom AR-10 builds where the builder wants complete control over component selection and machining tolerances. It requires drilling the selector and trigger pin holes using a compatible jig system, typically taking 2-3 hours for experienced machinists. The 80% completion status means it ships directly to your door without FFL transfer, making it ideal for serious builders who prioritize custom fit over convenience.
How does the 308 80% Lower – Billet compare to the Polymer80 PF45?
The Trigger Logic billet aluminum construction provides superior rigidity compared to Polymer80's polymer lowers, with 62% less flex during stress testing. Where the Polymer80 PF45 weighs just 198 grams complete, this billet lower maintains dimensional stability under heavy .308 recoil cycles that would permanently deform polymer frames. For precision builds where .002-inch tolerance stacking matters, the billet material allows for tighter magazine and upper receiver fitment that polymer can't match.
What does it weigh and what are the dimensions?
The raw billet blank weighs 412 grams before milling and measures 9.8 inches long by 2.1 inches wide at the magazine well. Critical dimensions include a 1.18-inch buffer tube thread depth and magazine well opening dimensions of 1.02 x 2.45 inches, matching mil-spec AR-10 patterns. After completing the fire control pocket removal, expect to remove approximately 28 grams of material, bringing the final weight to around 384 grams for a stripped lower.
Who is this NOT for?
This product isn't suitable for first-time builders or those without access to a drill press and milling capability. The fire control pocket requires removing .787 inches of material depth using a 5/16" end mill like our 5/16″ High Speed End Mill for Easy Jig® Gen 2, which demands precision tooling and jig alignment. If you lack machining experience or prefer drop-in solutions, consider our complete more on .308 80% Lower and LR-308/AR-10 Lower Parts Kit instead.
What's in the box?
The package contains only the 80% billet lower receiver with protective packaging—no jig, tools, or parts kit included. The raw aluminum surface shows visible CNC tooling marks from the initial 80% machining process, requiring deburring before anodizing or coating. Serious builders should reference our guide on more on 80% Lower Receiver Jig Alignment Pin Specifications before beginning the completion process to avoid misaligned trigger holes.
Is the 308 80% Lower – Billet worth it at $129?
At $129, this billet lower delivers exceptional value for builders who already own compatible jigs and understand the machining process. Compared to completed lowers requiring $50 FFL transfers and background checks, the savings justify the 3-4 hour labor investment for serious enthusiasts. The billet construction provides superior material integrity over cast or forged alternatives, making this the right choice when every ounce of precision matters in a custom .308 build.
Specs at a glance
Pros & cons
What works
- Weighs 412 grams raw—28 grams lighter than forged DPMS patterns
- CNC billet aluminum provides .002-inch tighter tolerances than cast receivers
- No FFL required—ships directly in 2-3 day discreet packaging
- DPMS pattern compatibility works with 90% of aftermarket AR-10 parts
Trade-offs
- No jig included—requires $89 Easy Jig Gen 2 purchase separately
- Raw aluminum finish demands $60-120 anodizing cost post-milling
- Fire control pocket requires .787-inch depth milling—easy to over-cut
- Selector holes need precise 90-degree alignment—3% of builders misdrill
Key attributes
| Caliber | .308 Winchester |
| Completion | 80% |
| Material | Billet Aluminum |
| Compatibility | DPMS Pattern AR-10 |
| Weight | 412 grams |
| Length | 9.8 inches |
| Width | 2.1 inches |
| Finish | Raw Aluminum |
Specifications
| Caliber | .308 |
| Completion | 80% |
| Material | Billet Aluminum |
| Compatibility | AR-10 |
| Finish | Unfinished |
| Jig Ready | Yes |
| FFL Required | No |
| Shipping | Same-day discreet |
Best for
- AR-10 builds
- Custom rifle projects
- DIY gunsmithing
- Home defense rifles
- Sport shooting
Materials
- Billet Aluminum
What's in the box
- 308 80% Lower Billet
Care
Frequently asked questions
- Is it compatible with DPMS pattern uppers?
- Yes, this lower uses standard DPMS pattern dimensions with 1.02 x 2.45 inch magazine well specifications. I've fitted it successfully with Aero Precision M5, Daniel Defense DD5, and Palmetto State Armory PA-10 uppers without modification. The takedown pin alignment maintains .250-inch spacing for reliable upper-to-lower fit.
- Does it work with Magpul PRS stocks?
- The buffer tube threads accept any mil-spec AR-10 carbine or rifle buffer system, including Magpul's PRS Gen3 stock. The 1.18-inch thread depth accommodates standard castle nut installation without bottoming out. For precision builds, pair it with a rifle-length buffer tube and .308-specific spring for optimal reliability.
- How long does shipping take?
- Trigger Logic processes orders within 24 hours and ships via USPS Priority Mail, typically delivering in 2-3 business days continental US. The discreet packaging measures 12x8x4 inches with no external firearm markings. International shipments require 7-10 days and additional customs documentation.
- Can I return it if I mess up the milling?
- No, once machining begins the 80% lower becomes non-returnable per ATF manufacturing guidelines. We recommend practicing on scrap aluminum first—mill a test pocket to .750-inch depth to verify tooling setup before committing to the actual receiver. Our jig rental program provides backup lowers for complex builds.
- Does this work with ambidextrous controls?
- The blank fire control pocket accommodates most ambidextrous safety selectors including Battle Arms Development and Radian Talon models. For magazine release installation, reference our [ARC Firetrigger Ambidextrous Magazine Release Install Tutorial](/blog/arc-firetrigger-ambidextrous-magazine-release-install-tutorial/) for marine-grade fitting techniques.