Difference between .223 and 5.56

Next thread will be can I fire 762 'nato' in barrel stamped 308 winchester, which reminds me, my car owners manual states I should use 87 octane from Esso all I can find is 87 octane from Chevron :)
 
I don't think it matters as much as some make it to be .Years ago (like 25) a friend of mine purchased a mini 14 in .223 rem . From this he shot thousands and thousands of rounds of surplus fmj ammo. He was a bit of an animal ten round bursts - the norm per groundhog. He then sold it even though it worked fine . I know the guy who bought it and it still ain't blown up.
 
As pointed out above, in Europe there is no difference, CIP data is for 5.56x45mm. There have been no rash of gun explosions caused by using US made 223 rifles with European CIP spec ammo. The warnings provided by US companies do two things. They increase commercial ammo sales, and they make corporate lawyers happy.
Military spec 5.56mm ammo is hotter than some commercial 223, but still within safe specs for firearms chambered in 223 except under very exceptional circumstances.
 
jennis said:
Next thread will be can I fire 762 'nato' in barrel stamped 308 winchester, which reminds me, my car owners manual states I should use 87 octane from Esso all I can find is 87 octane from Chevron :)
Click to expand...

I have a feeling that was sarcastic....

The .308 Winchester is the commercial/civilian equivalent of the military 7.62x51mm NATO centerfire cartridge. Though the .308 Winchester was introduced in 1952, two years prior to the NATO adoption of the 7.62x51mm NATO T65.

While the .308 Winchester and 7.62x51mm cartridges are not identical and there are minor differences in their inner case dimensions, SAAMI does not list either cartridge as unsafe in a firearm designed for use with the other.

If in doubt about which cartridge is safe for your particular firearm, always check with the firearm's manufacturer for direction.
 
“The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.” - SAAMI

CUP = Copper Units of Pressure, from before electronic transducer sensors.

The area around the C of R (the lead) is closer to the chamber in .223. The rifling in a 5.56 chamber is .164 from the case mouth, while the .223 is .045 from the case mouth. This means that longer 5.56 x 45 mm NATO bullets may "crush up" as the cartridge is chambered increasing pressure even more - in additon to increasing closing and locking force.
 
Some info from Winchester Ammo:

http://www.winchester.com/lawenforcement/news/newsview.aspx?storyid=11

5/4/2001
.223 Rem VS 5.56mm

There are a lot of questions about these two cartridges. Many people think they are identical - merely different designations for commercial and military. The truth is that, although somewhat similar, they are not the same and you should know the differences before buying either cartridge.

  • The cartridge casings for both calibers have basically the same length and exterior dimensions.
  • The 5.56 round, loaded to Military Specification, typically has higher velocity and chamber pressure than the .223 Rem.
  • The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.
  • The 5.56mm and .223 Rem chambers are nearly identical. The difference is in the "Leade". Leade is defined as the portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. It is also more commonly known as the throat. Leade in a .223 Rem chamber is usually .085". In a 5.56mm chamber the leade is typically .162", or almost twice as much as in the 223 Rem chamber.
  • You can fire .223 Rem cartridges in 5.56mm chambers with this longer leade, but you will generally have a slight loss in accuracy and velocity over firing the .223 round in the chamber with the shorter leade it was designed for.
  • Problems may occur when firing the higher-pressure 5.56mm cartridge in a .223 chamber with its much shorter leade. It is generally known that shortening the leade can dramatically increase chamber pressure. In some cases, this higher pressure could result in primer pocket gas leaks, blown cartridge case heads and gun functioning issues.
  • The 5.56mm military cartridge fired in a .223 Rem chamber is considered by SAAMI (Small Arm and Ammunition Manufacturers Institute) to be an unsafe ammunition combination.

Before buying either of these two types of ammunition, always check your gun to find what caliber it is chambered for, then buy the appropriate ammunition. Most 5.56mm rounds made have full metal jacket bullets. Performance bullets - soft points, hollow points, Ballistic Silvertips, etc. - are loaded in .223 Rem cartridges. Firing a .223 Rem cartridge in a 5.56mm-chambered gun is safe and merely gives you slightly reduced velocity and accuracy. However we do not recommend, nor does SAAMI recommend, firing a 5.56mm cartridge in a gun chambered for the .223 Rem as the shorter leade can cause pressure-related problems.

Winchester Law Enforcement Ammunition
 
THey should have just deleted .223 and stick with 556, and be done with it

BTW - IIRC 308 operates at high pressure than 7.62- the exact opposite to the situation of 223/556.
 
You must log in or register to reply here.
Back
Top Bottom