There is also a bunch of misinformation out there pertaining to this exact subject. However, there are some very subtle, yet important differences between the 223 vs 5.56mm cartridges that go far beyond the differences in their names. It is true that the two cartridges are very similar to each other. 223 Remington and 5.56x45mm NATO cartridges as interchangeable rounds, this can be a dangerous practice under the wrong circumstances. 223 vs 5.56x45mm NATO cartridges so you can use the right ammunition for your AR-15? Here’s what you need to know about their similarities and differences.Įven though many people treat the. Are you trying to learn the difference between the.