While there are also options to convert AR’s to a large number of pistol and rifle calibers, the standard .223 (5.56x45mm) is the best solution. (a comparison of calibers is outside the scope of this article) The .223 round is available and manufactured in greater numbers than any other round. In addition, different loads are available to fill a number of needs, from hunting small game up to long-range accuracy, tracers, incendiary and more.

It is perhaps the best round for CQB, surpassing any of the handgun rounds with more stopping power and less chance of over-penetration. It offers a flat trajectory, good penetration when necessary, and destructive effects on targets.

The 5.56mm NATO also offers a light recoil, and small size. This is important because you may need to carry and store a large amount of ammunition, and the light recoil aids in training and use by smaller or younger individuals.

As for loadings, either the U.S. M193 55 grain or the current NATO 62 grain, steel core will do (U.S. SS109). Preference goes to the 62 grain NATO round if it can be found. However, the 55-grain loadings are cheaper and more readily available. There are a number of other weights available, but do not offer any advantages for our general-purpose use.