The PAP M90 is chambered in the popular .556 round and will also shoot .223 both steel and brass cased ammo. There are 3 adjustable gas settings so you can quickly dial the rifle in to your ammo or muzzle device. As with all Zastava products the M90 is built like a tank featuring RPK style bulged trunnion and 1.5 mm thicker receiver. The hammer forged Zastava barrel is chrome lined to provide years of accurate shooting and range fun. Comes with the optic rail on the left side of the gun allowing you to add a mount and your favorite optic. The great stock is made by MAGPUL and side folds for storage.