My question is that a salesman told us that you may have trouble using 223 ammo in a AR-15 that is chambered for 556. I have been reading all I can about the Ar-15's be for I purchase one.My friend who has a Bushy said to get the AR-15 that will handle or chambered for 556 that way I can shoot both 223 and 556 ammo.? (Then this salesman at the gun shop said "if you get a gun chambered for 556 you may have a bunch of trouble with ejection the shell using 223 ammo!") I know you CANT shoot 556 in a gun marked 223 but you Can shoot 223 in a gun marked 556 cause 556 is beefed up and a more power full shell. I have a S&W 357 mag. pistol and I have no trouble shooting 38 special ammo But you could never shoot 357 mag. ammo in a pistol thats a 38 special.Hope this all makes sense , Iam new to the AR world and want to find out all I can befor I make the move..Thinking Stag,Bushy or Colt??? Thanks Ron Wanna kill these ads? We can help!