Palmetto State Armory is where I get most of mine. $12.00 shipping for 1000 rounds. They have XM193, XM855 and a lot of .223 available for around 300-315 per 1000. Make sure your upper has a proper 5.56 chamber, not .223 before you shoot mil-spec ammo though. 5.56 in a .223 chamber is asking...