RBC-9 Public Beta

Roller Delayed. Belt-Fed. 9mm. What More Could You Want?

Out of all the varieties of firearms given mythical status by both Hollywood and the ATF, the belt-fed has to be one of the most romantic images in our collective consciousness. Few have attempted to create these designs, and fewer still have succeeded and avoided the powers that be in the process, so you can imagine our unbridled excitement when we discovered the RBC-9 hiding right under our noses.

Concocted by Nopel, a long-time developer who made his fame on WeaponsGuild, and released as a public beta, this insanely complicated and totally homebrewed design has made massive waves in the community after being shown off on both Twitter and OutOfBattery Live.

We can’t help but join in on the chorus of praise. This is a must-have for advanced, intrepid builders who aren’t afraid of Full-DIY.

In The Wild

Photos

Videos

RBC-9 Public Beta v. B1 Technical Specs

The files are designed to accommodate PLA+ as a minimum, but documentation recommends stronger materials such as Nylon and printed Aluminum. Documentation also recommends specific print settings and orientation, and some parts are not printable on every machine. Durability may vary depending on selected print settings and printing materials.

Documentation is extensive and incredibly thorough, with a page count so high we had to compress the file twice to be able to host it here.

Other than using an AR-9 pattern barrel, which can be replaced with a homemade version, the project is Full-DIY, and can be completed without purchasing any firearms parts or completion kits.

RBC-9 Public Beta v. B1 Parts List

Hardware

• Rods/Pins
  • 1 – Mild steel rod (³⁄₃₂” D, >3′ L)
  • 1 – Hardened dowel pin (³⁄₃₂” D, >1″ L)
  • 1 – Hardened dowel pin (¼” D, >26mm L)
  • 1 – Hardened dowel pin (⁵⁄₁₆” D, >1″ L)
  • 1 – Mild steel rod (⅜” D, >2″ L)
  • 1 – Mild steel rod (½” D, >1′ L)
  • 1 – Mild steel rod (⅝” D, >4″ L)
  • 1 – Stainless steel rod (3mm D)
• Other
  • 1 – Mild steel flat stock (³⁄₁₆” THK, >1″ W)
  • 3 – Square stock (⁵⁄₁₆” THK, 1 ¼” L)
  • 1 – Paperclip
  • M3 melt inserts (5mm D, 7mm H)
  • 9 – MAGCRAFT magnets, disc (0.375″ D x 0.125″ L)
• Spacers
  • 1 – ⅜” OD, ¼” ID
  • 1 – ½” OD, ⅜” ID
  • 1 – ⅝” OD, ½” ID
• Springs (Hillman IDs, please see documentation for details)
  • 3 – #5
  • 1 – #71xa
  • 1 – #3
  • 1 – #90
  • 2 – #115
  • 3 – #139
  • 1 – #151
  • 1 – #174
  • 1 – #147
  • 2 – BiC mechanical pencil spring
• Screws
  • 26 – M3-0.5 x 10mm
  • 4 – M3-0.5 x 6mm
  • 4 – M3-0.5 x 30mm
  • 1 – M3-0.5 x 20mm
  • 1 – ¼” x 1 ¼”
  • 1 – ¼” x 2 ½”
  • 2 – ¼” x 2″
  • 1 – ³⁄₁₆” x 2″
  • 1 – M3 nylon locking nut

RBC-9 Public Beta v. B1 Build Instructions

The RBC-9 Public Beta is a fantastic opportunity for advanced builders to be a part of GunCAD history. Download and build one today!