Available at Airsoft Atlanta is the Angel Custom CNC Glock Threaded Barrel Adapter for attaching muzzle devices... "The Angel Custom CNC Glock Threaded Barrel Adapter - a 13mm CCW to 14mm CCW inner barrel adapter that allows you to attach flash hiders, tracer units, and suppressors to your VFC Glock. Works with VFC Elite Force Glocks (VFC types: all G17, G19, G19x, G18c, etc and possibly other EF types (KWC) we haven't tested yet). Includes rubber o-ring to help stabilizer the adapter. Aluminum metal construction.

Be sure to install the CCW direction as to not strip threads. Be sure inner barrel is completely free and clear of debris/plastic before installing.  Installation voids warranties. Official Angel Custom airsoft part."