The TRYBE Defense AR-15 10.5in Upper is chambered in 5.56 and will safely shoot both 5.56 and .223.
.223 can be fired in any firearm marked 5.56, but 5.56 should only be fired in a gun marked 5.56.
5.56 has higher pressures than .223 and supposedly may hurt the gun if fired.
But the pressure location on each case is different and that may be why they are different.
Dimensionally exterior size are interchangeable.