I have a 20" A1 barrel for sale, with birdcage FS. It is an FNMI A1 barrel (light under handguards) - $112.00 shipped, continental US only. Payment accepted is MO or PayPal (add 3.5% for PayPal). Includes FS, FSB, barrel nut, slip ring, and gas tube. FNMI barrel is marked FNMI MP Chrome Bore. I believe the twist is standard A1 1/12 twist. E-mail for photos.