Ammunition is getting pricey. Rising fuel prices, the price of metals and inflation are increasing the cost of ammunition. I’ve done almost all my ammo shopping online, particularly for bulk.223 ammo. The best prices for ammo nowadays are online, and in bulk. If you can manage to buy  500 to 1000 rounds of your ammunition of preference you’ll save a lot. Check out this website for a great price in ammunition.

Ammo is not ammo, and when you do a side by side comparison with the .223 and 5.56 you will see the difference. Although they may look the same they are not.

The comparison between .223 and 5.56 isn’t a new one, so there is a lot of discussion to weed through to learn about the two. Ultimately, because they originated from the same cartridge, they are very similar, but that does not mean that they are necessarily interchangeable. This article discusses three key differences between .223 Remington and 5.56x45mm NATO.


.223 Remington and 5.56x45mm Dimension Measurements

At a glance, the two rounds are indiscernible. Both rounds use a bullet of .224in in diameter and an overall length of 2.26in. In general, the external


dimensions for the two calibers are identical. What’s more significant is the pressure of the two rounds and the difference in the rifle chambering.


.223 Remington and 5.56×45 Pressure Measurements

One of the problems with comparing these two cartridges is that they utilize different methods of measuring pressure. SAAMI (Sporting Arms and Ammunition Manufacturers’ Institute) measures the .223 pressure at the center of the casing, whereas the NATO standard measures the pressure at the throat (or leade) of the chamber. To rectify the two different methods, several have undertaken experiments with their own standardized recording method to compare “apples to apples.” One such thorough study was carried out and recorded in detail by Andrew Tuohy posted via Lucky Gunner Labs (click here to read the full article). Tuohy evaluated various .223 and 5.56 ammo fired through rifles chambered for .223 Remington and 5.56x45mm.

His, and the research of others, confirms that, generally, shooting .223 through a 5.56 chamber results in lower pressure, but still functions (safely). Firing 5.56 through a .223 chamber, however, results in somewhat higher pressures. Although the differences aren’t massive (~5% in the previously referenced study), extensive firing of 5.56 through a .223 chamber could lead to over-pressure malfunctions, such as popped primers or blown cartridge case heads and other firearm malfunctions.

Here’s a video comparing the two bullets:








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