Difference Between 5.56 and 223 (With Table)

Rifles and bullets fascinate a lot of people. Therefore, knowing the differences between the 5.56 NATO and the 223 Remington is important. Both of these belong to the family cartridge and are very much similar. There are small differences between the two, but those are highly impactful.

There are a ton of articles written on this topic. As 5.56 and 223 are much in demand but causes problems in identifying them.

5.56 vs 223

The main difference between 5.56 and 223 is that the 5.56 NATO Cartridge has a high-pressure level which is 58,000 psi approximately. On the other hand, 223 Remington has a pressure level of 55,000 psi approximately. Also, 5.56 NATO has a longer throat of .125’’ than 223 Remington.

Difference Between 5.56 and 223

The 5.56 X 45mm (5.56) NATO Cartridge (spell as five five-six) belongs to the family of intermediate cartridges. In the year 1980, it was announced to be the second standard service rifle under cartridge for NATO members as well as non-NATO members. It is the modified version of .223 Remington.

The 223 Remington is a bottlenecked and rimless rifle cartridge. It is the most popular rifle cartridge used in various manual-action rifles, semi-automatic rifles, and handguns. The 5.56 NATO cartridge was developed from 223 Remington. In 1957, it was developed for the army of the United Nation for the United States Continental Army Command.

Comparison Table Between 5.56 and 223

Chamber dimensionThe chamber of the 5.56 NATO, known as the mil-spec chamber, has a longer leade.The chamber of the 223 Remington, known as the SAAMI chamber has a shorter leade.
DiameterThe bullet diameter is 5.70 mm or 0.224 inches. The land diameter is 5.56 mm or 0.219 inches. The neck diameter is 6.43 mm or 0.253 inches. The base diameter is 9.58 mm or 0.377 inches. The shoulder diameter is 9.00 mm or 0.354 inches. The rim diameter is 9.60 mm or 0.378 inches.The bullet diameter is 5.7mm or 0.224 inches. The land diameter is 5.6 mm or 0.219 inches. The neck diameter is 6.43 mm or 0.253 inches. The base diameter is 9.6 mm or 0.376 inches. The shoulder diameter is 9.00 mm or 0.354 inches. The rim diameter is 9.60 mm or 0.378 inches.
Length The case length is 44.70 mm or 1.760 inches. The overall length is 57.40 mm or 2.260 inches.The case length of 223 Remington is 45 mm or 1.76 inches.
ThicknessThe thickness of the rim is 1.14 mm or 0.045 inches.The thickness of 223 Remington is 1.1 mm.
Capacity It has a capacity of 1.85 cm cube. It has a capacity of 28.8 grain H2O or 1.87 ml.
Pressure430 MPa or 62,366 psi.380 Mpa or 55,000 psi.
Speed3.56 g XM193 FMJBT has a velocity of 993 m/sec and energy of 1,755 J.
4 g SS109 FMJBT has a velocity of 993 m/sec and energy of 1,797 J.
4 g M855A1 FMJBT has a velocity of 961 m/sec and energy of 1,859 J.
2 g JHP has a velocity of 1,140 m/sec and energy of 1,300 J.
4 g Nosler ballistic tip has a velocity of 990 m/sec and energy of 1,715 J.
4 g Nosler partition has a velocity of 960 m/sec and energy of 1,796 J.

What is 5.56?

FN Herstal has developed the 5.56 X 45 mm NATO cartridge in Belgium, between the years 1970 and 1980. It was in service from 1980 and used mostly with rifles, DMR (Designated Marksman Rifle), LMG (Light Machine Gun), and carbine.

In those countries which are members of NATO (North Atlantic Treaty Organization), and in non-NATO countries like Japan, Taiwan, Australia, South Korea etc. 
The 5.56 NATO has a 62-gram lead core bullet with a steel penetrator that can penetrate up to 51 cm into the soft tissue under an ideal environment. It has a cartridge case capacity of 28.5 gained H2O. It can handle up to 420 MPa pressure. One of its kind is the 7.62 NATO which has twice the energy than 5.56 NATO.

What is 223?

Remington Arms and Fairchild Industries developed the 223 Remington cartridge in 1975. They created this cartridge under a project of creating high velocity and small calibre firearms for the United States Army Command of the U.s Army. 

The 223 Remington has become a very popular cartridge and works with rifles. It has been in use since 1962. The 5.56 x 45 mm NATO and .223 Ackley Improved are its variants. The parent of the 223 cartridges is the .222 cartridge. The US Army refers to the 223 Remington as, Cartridge, 5.56 mm ball M193. 

Main Differences 5.56 and 223

  1. The SAAMI pressure in 5.56 X 45 mm NATO Cartridge is slightly higher than 223 Remington.
  2. The 5.56 X 45 mm NATO cartridge loaded with a bullet weight of 86 grains, while 223 Remington loaded with a bullet weight of 56 grains.
  3. The chamber of 5.53 NATO cartridges is larger than the chamber of 223 Remington.
  4. If the barrel is marked 5.56, it can fire 5.56 and .223. On the other hand, if a barrel is marked .223, it can fire only .223.
  5. The throat in 5.56 NATO is longer and has more powder capacity than that of 223 Remington.


The properties of 5.56 x 45 mm NATO and 223 Remington are mostly the same. There are only two or three differences between them. 5.56 is the modified version of 223 Remington. But it is important to know the differences.


  1. https://shsu-ir.tdl.org/bitstream/handle/20.500.11875/1169/0785.pdf?sequence=1
  2. https://www.astm.org/DIGITAL_LIBRARY/JOURNALS/FORENSIC/PAGES/JFS12476J.htm
One request?

I’ve put so much effort writing this blog post to provide value to you. It’ll be very helpful for me, if you consider sharing it on social media or with your friends/family. SHARING IS ♥️

Ads Blocker Image Powered by Code Help Pro

Ads Blocker Detected!!!

We have detected that you are using extensions to block ads. Please support us by disabling these ads blocker.