Understanding 223 vs. 5.56: Are They Interchangeable? ~ VIDEO

The video gave a lawyer's answer couched in technical terms.

99% of the discussion about ".223 vs 5.56mm" centers on 5.56mm having a higher chamber pressure than .223 Remington. But the numbers generally cited are comparing apples and oranges because the milspec pressure standard is measured differently from the SAAMI pressure standard. Yes, the standard pressure for 5.56x45mm NATO ammo is higher than the pressure for .223 Remington even when they are measured the same way, but not as much as the numbers usually shown.

The next part of the problem is that there hasn't been a mass produced rifle with a chamber that follows the .223 Remington specification in decades. There are dozens of slightly different specifications being used, but most barrels are actually chambered for .223 Wylde which is basically halfway between a true .223 Remington and a true 5.556x45mm NATO milspec chamber. The ".223 Wylde" chamber is perfectly safe with 5.56mm ammo that meets the NATO spec. (Note however that not all US military 5.56mm ammo meets NATO spec, resulting in overpressure even when fired in a US military rifle)

The Commission Internationale Permanente pour l'épreuve des armes à feu (C.I.P.) sets standards for civilian ammunition and weapons in Europe. The C.I.P. is similar to the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) in the United States. Interestingly enough, although SAAMI treats .223 Remington and 5.56x45mm NATO as completely different cartridges, CIP (their European equivalent) treats the two as being two different names for the same cartridge - which is why most European ammo shows both names on the box.

Thanks, MSG Thomas Currie. I wasn't expecting another deep dive on the .223/5.56 saga but it's probably good that you took the time and concern to refresh older minds and educate younger ones.

MSG Thomas Currie
good info. TY

Lol, Corecto Mundo