The Stern Defense 9mm Complete Bolt is a pistol-caliber conversion bolt from STERN DEFENSE (brand part no. 004-SD EUBU9D1M) built to run 9mm ammunition in a properly configured AR-platform upper, in place of the standard 5.56/.223 bolt carrier group. It is labeled by the manufacturer for semi-auto only use and finished in black.

Key Specifications

• It is a complete 9mm conversion bolt that replaces the standard bolt carrier group in a properly configured AR-platform upper.
• Pistol-caliber AR conversions like this run on straight blowback operation rather than the gas-impingement system used for 5.56/.223.
• It is labeled by the manufacturer for semi-auto only use.
• It is finished in black.

Frequently Asked Questions

Does this work in any AR-15 upper? No, a 9mm conversion bolt requires a properly configured 9mm upper (with the correct barrel, magwell block, and blowback-compatible parts), not a standard 5.56/.223 upper.

What does ‘semi-auto only’ mean here? It is the manufacturer’s own labeling for this bolt’s intended function, describing standard semi-automatic operation only.

Buy the Stern Defense 9mm Complete Bolt, Black, Semi-Auto

Browse the Stern Defense 9mm Complete Bolt, Black, Semi-Auto in our Rifle Parts lineup at Schaefer Defense; we ship it fast and fully insured from our Lubbock, TX gun shop.