Here is the way I "Squib" load the 223
There are several ways to down-load the 223.
You can load either 4.0 to 5.0 grains of Bullseye.
I use 5.6 grains of Unique [1850 feet per second].
You can use your "regular" powder by sending $5.00 to Lee for their SQUIB load program. If you have their MODERN RELOADING by Richard lee, you can find information for it on pages 90 to 93.