NOBU v2 3D Printed Lower Receiver for BC-9 Bufferless

Overview

The NOBU v2 represents a significant evolution in 3D printed lower receivers, specifically engineered for Bear Creek Arsenal's BC-9 Bufferless AR-9 platform. This innovative design eliminates common failure points while delivering exceptional performance and reliability.

Built as an enhanced remix of the popular UBAR-9 lower receiver, the NOBU v2 features a printed butt cap that completely eliminates the need for the adapter piece included with the BC-9. This streamlined approach results in a more robust and reliable platform compared to the original NOBU design.

NOBU v2 3D Printed Lower Receiver for BC-9 Bufferless Features

The redesigned architecture focuses on structural integrity by removing the problematic adapter piece integration that plagued the original version. This elimination of unnecessary components creates a solid performer that has proven reliable in testing.

Key design improvements include:

Integrated butt cap design that replaces the factory adapter
Enhanced structural integrity through simplified component integration
UBAR-9 compatibility while maintaining unique BC-9 Bufferless optimization
Proven performance track record from extensive field testing

The streamlined bolt pattern utilizes a combination of M5 and M4 socket head bolts for secure assembly, replacing the traditional U-bolt and eye bolt configuration found in standard UBAR builds.

Difficulty & Build Time

Skill Level: Intermediate to Advanced
Estimated Build Time: 8-12 hours (including print time and assembly)
Required Experience: Previous 3D printing experience and familiarity with AR platform assembly recommended

Hardware and Tools Required

Required Hardware

(2x) M5x45 socket head bolts for primary structural connections
(1x) M5x50 socket head bolt for extended reach applications
(2x) M4x35 socket head bolts for secondary mounting points
(3x) M5 nuts for bolt securing
(2x) M4 nuts for M4 bolt applications
(1x) M2x16 bolt as replacement for original roller pin
All standard UBAR9 components (excluding U-bolt and eye bolts)

Recommended Tools

3D printer capable of printing receiver-sized components
Hex key set for socket head bolt installation
Drill and bits for any required hole finishing
Files and sandpaper for post-processing
Torque wrench for proper bolt tensioning

NOBU v2 3D Printed Lower Receiver for BC-9 Bufferless Parts

The design package includes precision-engineered STL files optimized for home 3D printing with standard FDM printers. The integrated butt cap geometry requires careful attention to print orientation for optimal layer adhesion and structural integrity.

Print settings should prioritize strength with higher infill percentages and appropriate layer heights for dimensional accuracy. The design accommodates standard printing capabilities while maintaining the tight tolerances required for proper BC-9 Bufferless integration.

Printer Compatibility & Settings

Compatible with most FDM 3D printers with build volumes sufficient for lower receiver printing. PLA+ or ABS materials are recommended for optimal strength and durability, with PETG serving as an excellent middle-ground option.

Print orientation should follow established lower receiver best practices, with 100% infill recommended for critical stress-bearing areas. Layer heights of 0.2mm or finer ensure proper surface finish and dimensional accuracy for hardware fitment.

Conclusion

The NOBU v2 represents a mature evolution of 3D printed lower receiver design, specifically addressing the unique requirements of the BC-9 Bufferless platform. By eliminating problematic adapter integration and focusing on proven structural principles, this design offers reliable performance for serious builders. The comprehensive documentation and hardware specifications ensure successful builds for those with appropriate experience and equipment.