New  Kel-Tec SU16 18.5" 5.565.56/.223 includes (2) 10rd mags but will use any AR mags.  Ammo available with purchase.  REDACTED Shipping $40 to your local FFL. 

The SU-16A is a gas operated, semi-auto loading rifle chambered in 5.56 mm NATO caliber. It is intended to be the perfect everyman's sport and utility rifle. It has a 1:9" RH twist. Several features make the SU-16A a versatile sporting firearm, including a chrome-lined bore and chamber and integrated Picatinny rail for mounting different sight systems. The forend folds down to form a bipod for increased accuracy, the stock can store spare magazines, two 10-round magazines and trigger mechanism can be folded forward for added safety and to facilitate secure storage or carry under extreme conditions. Except for barrel and operating components, the SU-16A is made entirely of high impact reinforced polymer.