5.56 and 223

[KnotRight]

I have not bought 223 ammo in over 4 years but was having a problem with one of my ARs so I bought some factory ammo.

I always thought that 5.56 ammo was loaded hotter than 223. When I reload I never look at the 5.56 section of the reloading manual. As you can see below, the same weight bullet in 223 is 75 ft/sec faster than the 5.56. Is this normal?

 

[AR10ShooterinNC]

In the civilian world, I do not think there much difference between the two in loaded ammo. 556 loaded to NATO specs is going to hotter than 223.

 

[WadeWatts]

The .223 test barrel was probably longer. Military spec barrels are pretty short and .223 hunting barrels are typically longer

 

[CZfool68]

https://www.luckygunner.com/labs/5-56-vs-223/


https://www.shootingillustrated.com/articles/2018/7/28/556-nato-vs-223-rem-whats-the-difference/