Question: what is the difference between a 223 and a 5.56 nato round?
Answer: 223 rounds are virtually identical in size to 5.56mm rounds. This means that the majority of the time, . 223 ammunition will chamber and fire in a 5.56mm chamber and vice versa. However, the biggest difference between the two is that 5.56x45mm ammunition is loaded to a significantly higher pressure than .