SL-308 V3.9

SL-308 V3.9 Features

This redesigned 3D printed LR-308 lower receiver stands out with its integrated grip, which eliminates the need for separate attachments and streamlines the overall build. It inherits the same ergonomics as the SL-15, ensuring familiar handling for users experienced with AR-15 platforms, while the slimmer profile reduces bulk without sacrificing strength.

• Fully Redesigned Structure: Based on the V4.8 SL-15 lower, optimized for LR-308 compatibility and enhanced durability.
• Practical Enhancements: Includes files for bushings and plates, supporting both printed and machined components for a hybrid build approach.
• Customization Focus: Designed for 3D printing enthusiasts, with options for metal machining to boost performance in high-stress areas.

These features make the SL-308 V3.9 unique for Hoffman Tactical fans, blending 3D printing innovation with firearms reliability. The inclusion of detailed drawings and STLs ensures a precise fit for standard parts.

Difficulty & Build Time

• Skill Level: Intermediate
• Estimated Build Time: 8-12 hours (including printing, machining, and assembly)
• Required Experience: Basic 3D printing knowledge, familiarity with lathe operations for bushings, and experience with metal machining for plates

Hardware and Tools Required

Required Hardware

• 0.375" diameter brass stock for machining bushings
• 6-32 brass insert (e.g., McMaster-Carr 97171A140)
• 6-32 x 1/2 screw with 0.250" wide hex head (e.g., McMaster-Carr 92314A148)
• Metal stock for machining front plates (based on provided STEP and PDF files)

Recommended Tools

• Lathe for turning bushings
• 5/32 drill bit and cut-off bit for bushing fabrication
• 3D printer for STL files like the bushing installation tool and printer-optimized plates
• Tools for cold pressing inserts and assembling components, such as pliers or a vise

SL-308 V3.9 Parts

The SL-308 V3.9 file includes essential STL files, such as the design for the bushing installation tool, which should be printed using PLA+ material for durability. Recommended print settings mirror standard guidelines from the main docs, featuring three walls and 25% honeycomb infill to ensure structural integrity without excessive material use. Special considerations include cold pressing the 6-32 brass insert into the knob and using the screw to secure it into the handle for a functional tool.

Additionally, STL files for the printer-optimized version of the front plates are provided, offering an alternative to the machining-optimized STEP and PDF files. These printed parts allow for quick prototyping, while the bushing PDF drawing supports custom fabrication on a lathe. Always refer to the build instructions PDF for assembly details, ensuring all parts align with LR-308 specifications.

Printer Compatibility & Settings

The SL-308 V3.9 is compatible with standard FDM 3D printers, making it accessible for most hobbyist setups like Ender or Prusa models. Recommended materials include PLA+ for tools like the bushing installer, providing the necessary strength and heat resistance for installation tasks. Print settings should follow standard parameters with three walls and 25% honeycomb infill; no special requirements beyond ensuring good bed adhesion and layer cooling to prevent warping in detailed components.

Conclusion

In summary, the SL-308 V3.9 delivers exceptional value for 3D printing and firearms enthusiasts by offering a slimmer, ergonomic LR-308 lower receiver that's easy to customize with included files for bushings and plates. Its blend of printed and machined elements ensures a robust build, ideal for Hoffman Tactical projects. Download the build instructions PDF to get started, and explore further upgrades for your AR-10 style rifle.