If you have been shopping around for one of the many popular military-style rifles at a gun shop, such as an AR-15 or a Ruger Mini 14, you likely have noticed differences in the ammo they are designed to use. Some list the .223 Remington as the cartridge to use. Others might list the 5.56 round, and many will list both.
What is the difference between the 5.56 and the .223 rounds? At an initial glance, not very much. Yet, their very small differences add up to a very big difference in shooting performance and safety. The following gives you a closer look at those differences and what they mean for shooting performance and safety.
5.56 Holds More Powder
The 5.56x45mm round is the same one used in the military’s M4 carbine. It is 0.125ths of an inch longer than the .223 Remington cartridge used in the civilian AR-15 and other military-style rifles.
That tiny difference in cartridge length enables the 5.56 round to hold one grain more of gunpowder than the .223. It also enables the 5.56 to produce 58,000 PSI of pressure versus 55,000 PSI for the .223 Remington. That additional length and pressure might not seem like much, but many civilian military-style rifles are not designed to handle that additional pressure.
If you use 5.56×45 rounds in a rifle that is not designed for it, you risk damaging the rifle and possibly injuring yourself due to a catastrophic failure. Yet, a rifle designed for the 5.56 round can use the .223 Remington quite safely.
Shooting Performance Might Lag With .223
Another way in which you might see a significant difference between the 5.56 and the .223 rounds is in their shooting performance. Because the 5.56 is a slightly hotter round, it goes a little faster and farther with a slightly flatter trajectory.
When you are shooting up close, there will be virtually no difference in performance. That changes the farther away your target is and especially if you sighted in your rifle while using a 5.56 round. The .223 will drop slightly sooner and produce wider groups at a distance than the 5.56 round.
It is important to sight your rifle using the correct ammunition and the same ammo you would use in the field. If you are a hunter, that makes all the difference between hitting your target in the vitals or running a greater risk of having to track a wounded animal.
Harrison Street Pawn and Gun in Paola, KS, has a great selection of long guns, shotguns, and pistols. Our pawn shop carries a great selection of ammo, including 5.56 and .223 for your military-style rifle. You can stop in and check out our inventory of firearms and ammunition. We are an FFL firearms dealer and are open from 9 a.m. to 6 p.m. Monday through Saturday.