The Franklin Armory BFSIII M4-BLR (brand part no. 00-30043-BLK) is a complete AR-15 lower receiver built around Franklin Armory’s proprietary BFSIII binary firing system, ready to mate with any standard mil-spec upper. It ships as a finished, ready-to-build unit rather than a stripped shell, so builders can pair it with an upper of their choice and get shooting fast. The black finish, SBM4 stabilizing brace, and included 30-round magazine make this a turnkey option for a pistol-configuration AR build. It’s a strong pick for shooters who want the BFSIII trigger response without sourcing and assembling a lower parts kit themselves.

Key Specifications

• The receiver is multi-caliber compatible, accepting standard AR-15 uppers across common chamberings without modification.
• It runs Franklin Armory’s BFSIII binary firing system, a legal semi-automatic trigger that fires one round on the pull and one round on the release, doubling practical rate of fire without leaving semi-auto operation.
• An SBM4 pistol stabilizing brace is installed, giving a stable shooting platform for a pistol-length build.
• It ships with one 30-round magazine, so you’re ready to load and go out of the box.
• Rated capacity is 30+1 rounds with the included magazine.
• A manual safety selector is fitted standard for on-safe carry between strings of fire.
• The lower carries a matte black finish that matches most mil-spec upper receivers.
• This is a complete, built lower rather than a stripped receiver, so no additional lower parts kit or brace purchase is required.

Frequently Asked Questions

Does the BFSIII trigger fire more than one round per trigger pull? No. It remains semi-automatic — one round fires on the pull and a second on the release, which is legally distinct from automatic fire.

Does this lower include a magazine? Yes, one 30-round magazine ships with the unit.

Is this a stripped or complete lower? It’s a complete, built lower receiver with the SBM4 brace and BFSIII trigger already installed.

Buy the Franklin Armory BFSIII M4-BLR Complete Lower Receiver

Skip the parts-kit assembly and drop a mil-spec upper straight onto this BFSIII-equipped lower, part of our AR15 lowers selection. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.