For most shooters the difference between .223 Remington and 5.56×45 NATO is minor, but it matters because 5.56 is typically loaded to higher pressures and uses a slightly different chamber leade.

Some cartridge comparisons like the “308 vs 556” can seem ridiculous because the two cartridges are so different in size, power, and performance. However, both cartridges have a military lineage, and ...