80% Builders Set – Upper/Lower W/ 10in rail


  • Upper and lower showing tooling marks.
  • Rail has Factory Anodizing

Cerakote Option-

  • Upper lower and rail color matched



RB80 Builders Set – Upper/Lower w/10in rail.


R&B Arms First Official 80% billet upper and lower combo, to be finished by the end user. The RBA80 is precision CNC-machined from billet 6061 aluminum for us. Billet receivers provide a significantly higher level of quality due to the stability of the raw material. Our RBA80 features our signature R&B Panda and our Behind enemy lines logo. Even though we are in California doesn’t mean we have the same thoughts and ideas as them.

Simple. Clean. Affordable.

Slick-Side upper omits the traditional forward assist, shell deflector and dust cover for a clean and simple addition to any AR-15 build. Slick-Side upper is precisely machined from premium, billet 6061 aluminum to ensure the tightest tolerances, in many cases, exceeding mil-spec requirements. Compatible with both forged and billet lower receivers as well as most types of fore-ends and quad rails.

  • T6 Heat-Treated 6061 Billet Aluminum – Raw finish (As machined)
  • Flared magwell to improve mag changes
  • Billet quality in a simplified form factor
  • Proprietary magazine geometry eliminates poor quality broaching
  • 100% USA Made
  • Available in Raw, or Cerakoted Options (Cerakote Options include Rail,upper and lower)
  • Custom Cerakote patterns and colors are an option, please contact us first.
  • Comes with 10in guntec rail (AIR-LOK Series M-LOK Compression Free Floating Handguard With Monolithic Top Rail (Gen 2) (Anodized Black)

Our goal is to produce a quality product at an affordable price. Machining marks are perfectly acceptable and agreed to with the purchase of this product.

Because 80% Lowers are not considered firearms by ATF, we can ship them right to your front door with no FFL required. Finished rifles must meet all applicable laws and you must be able to legally own a firearm. Compliance with all federal and local laws is YOUR responsibility.

We ARE NOT able to ship this product to anyone residing in the state of New Jersey.

Required machining to complete an 80% lower includes: Selector hole, Trigger pin hole, Hammer pin hole, Take-down lug slot, Fire control group pocket, Trigger slot


Raw, OD Green, FDE, Black, Sniper Grey


RAW, OD Green, FDE, Black, Sniper Grey


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