Hello,

Thank you for downloading the Hoffman Tactical AR-15 Double Rib Super Lower! This is V3.0.3. Based off of the V3.0 AR-15 Super Lower.

This lower is not compatible with uppers that use a forward assist. It is intended for use with slick side and side charging uppers only. To use almost any upper, instead print the AR-15 Super Lower with one support rib.

There are ten 3D design files in this download. The .STEP files may be opened in most CAD programs and edited. The .STL files may be imported into any slicer programs. For printing, use the .STL files.

The "Gen Two Head Plate" and "Gen Two Tail Plate" are the front plates that support the front take down pin.

"BL" means "Basic Lower". "SL" means "Super Lower". "NS" means "No Support". "WS" means "With Support".

The Basic Lower does not require the brass bushings or pistol grip threaded insert. You must tap the pistol grip thread with a 1/4 - 28 tap. The Super Lower requires the brass bushings and insert. No tapping is needed. You should use the file with support (WS). The support material is designed into the model. No support need be added while slicing. The file without support (NS) is intended for advanced users who desire to experiment. It does not include the designed in support. All lowers should be printed in the upright position with the bottom of the mag well against the print surface.

The front pin plates should be printed with their inside surface against the bed.

The Double Rib AR-15 Super Lower uses all of the same parts as the AR-15 Super Lower with one important exception. The hose clamp is larger. A #28 clamp is used rather than the #24 clamp on the single ribbed AR-15 Super Lower. This is the same clamp that the LR-308 Super Lower uses.

The built in support is designed for use with a 0.4 MM nozzle and 0.45 MM wide outside perimeters. 0.2 MM layer hight is recommended. Three walls and 100% aligned rectilinear infill should be used.

PLA+ or Carbon Fiber Nylon is recommended.

All lowers require the installation of a hose clamp to reach proper strength. A "mil-spec" buffer tube that has enough threads to work with the wide buffer tower is required. Buffer tubes that have no extra threads will not fuction properly.

For printing and slicing notes: https://hoffmantactical.com/slicing/ For assembly instructions: https://hoffmantactical.com/assembly/ To buy parts: https://hoffmantactical.com/shop/

Happy printing!