Like the others, the new .223 Rem load uses an all copper bullet that provides excellent expansion and weight retention while avoiding any problems with laws regarding the use of lead core ammunition. In the case of the .223, the cartridge uses a 60 grain bullet. According to SIG SAUER, you can expect deep penetration and an expansion to about 1.8x with these bullets.
One thing to keep in mind is that all copper bullets tend to be longer than lead core bullets of the same weight. This is because lead is denser than copper. So, keep that in mind when matching barrel twist rates with your cartridge selection. SIG states the bullet was specifically designed to ensure reliable feeding in AR style rifles.
SIG SAUER loads this round to 3,100 fps at the muzzle. That works out to be about 1,280 ft-lbs of energy.
The company uses a reduced flash propellant for hunting at dawn and twilight. The company uses premium quality primers and electromechanical checks on the powder level to provide very good shot to shot consistency. Additionally, SIG uses nickel plated cases with these rounds.