The Firing Line Forums - View Single Post - proper way for breaking in an AR-15

dsa1115 · May 7, 2010, 12:23 AM

don't use 5.56 ammunition in a gun chambered for .223 because of higher pressures of the 5.56. But you can use .223 ammunition in a gun chambered for 5.56 There is a difference of about 10,000 CUP between these cartridges.

May 7, 2010, 12:23 AM	#2
dsa1115 Senior Member Join Date: March 10, 2010 Location: Illinois Posts: 444	don't use 5.56 ammunition in a gun chambered for .223 because of higher pressures of the 5.56. But you can use .223 ammunition in a gun chambered for 5.56 There is a difference of about 10,000 CUP between these cartridges.