This Sylvan Arms conversion block (mfr. part no. GCB100) is a drop-in block that lets a mil-spec AR-15 lower accept 9mm Glock-pattern magazines, installing almost exactly like a standard rifle magazine.

Key Specifications

• Converts a mil-spec AR-15 lower to accept 9mm Glock-pattern magazines.
• Drop-in fit, no permanent modification required.
• Installs almost exactly like a standard rifle magazine.
• Chambered for 9mm Luger.
• Constructed of black steel and 6061-T6 aluminum.
• Weighs approximately 0.35 lb.
• Ships as a single (1) unit.
• Does not hold ammunition itself; it accepts a separate 9mm Glock-pattern magazine.
• Manufactured by Sylvan Arms.

Frequently Asked Questions

Does this block hold ammunition on its own?

No, it converts your AR-15 lower to accept a separate 9mm Glock-pattern magazine; it isn’t a magazine itself.

Do I need to permanently modify my lower to install it?

No, it’s a drop-in fit that installs almost exactly like a standard rifle magazine.

Buy the Sylvan Arms 9mm Conversion Block

Shop the Sylvan Arms lineup or browse our full AR Lower Parts selection to find the right fit for your firearm.