5.56 or 223

Read the first line in the description, it states "The cartridge casings for both calibers have basically the same length and exterior dimensions."

So how could it be possible for a case neck to get pinched in the throat or leade of the chamber. Makes no sense to me.

No where in this article does it state that the case neck can be pinched.

Plus the word "MAY" gets used here twice which to me, means it's possible due to the many number of chambers out there and they don't want to take any chances. Better safe than sorry for them.

Here is the article in full.



Law Enforcement News and Press Releases Details


News and Press Releases

.223 Rem VS 5.56mm

Paul Nowak
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
 
I didn't see anything in there about pinching a case neck . Did you?

Quote:
Keep shooting them and eventually you may have the opportunity to join the broken bolt club.




I never said I shot them in my AR, I use .223 Rem.
Would I be afraid to shoot them? No.
I've got a full bull barrel, and the bolt has been tested to 5.56 proof round standards, so the chances of "breaking" a bolt (I assume the locking lugs would shear first, eh?) is a pretty remote possibility.
Like I said, in a .223 bolt, pump or lever action rifle, the warning should be heeded. They may have been designed to only handle .223 Rem pressures, and they don't proof test them to 5.56 NATO standards.

Winchester does not produce an AR, which could explain their take on the subject.

I've shot a lot of 5.56 NATO through my Mini-14s, though, which are marked .223 Rem. and they aren't showing any ill effects. Never had any kind of malfunction, either. I have serious doubts their bolt design is any stronger than an AR, and the breech isn't any bigger.

Go figure, huh? /ubbthreads/images/graemlins/confused1.gif
 
Although Mini-14 are marked .223, they really have a 5.56 chamber. The manual that comes with the gun indicates it is safe to fire both. I think marking them a .223 is a 'political correct' tactic on their part. They don't want anyone to think they are making assault rifles.
 
All this 223 vs. 5.56 started in the 80's when the goverment tried to makr the 5.56 a long range gun. Before that military ammo had 55 grain bullets. Back in the 60 when Remington brought out the 223 they used the specs for the 5.56 with a 55 grain bullet. The old gov. m16 had a 1-12 twist barrel also. In the 80's the went to the 69 grain bullet they use today. That's when they went to the 1-9 twist barrel they also incresed the thoart length. Also up the pressures to get the vel. up. So this all means that the 223 vs the 5.46 is the same just a differnet bullet. Since most chambers are way longer than ecs SAMI specs anyway the firing of 5.56 in a 223 chamber should be just fine. Unless you have a custom gun with a short thoart.
 
The freebore diameter in a reamer for .223 is .2240 to .2245 in the various chamberings. In a 5.56 JGS , PTG nato it is .2265 in a clymer nato it is .2270.
The case mouth diameter is as low as .2510 in a remington match chamber
while the nato chamberings are .2540 and 2550. You can see with thicker brass
and smaller neck and throat openings how the problem can arise.
 
Many thousands (millions) of mil-surp rounds have been fired out of .223 chambered ARs with no ill effects. That's reality.

I read somewhere long ago that the problem is more likely to occur in NATO ammo made in other countries as apparently not all are the same.

Having said that, SAAMI says don't do it http://www.saami.org/Unsafe_Combinations.cfm. , and I agree with Hidalgo. If I was a full auto guy I would probably feel differently, but I don't see much advantage to using mil-surp ammo and definitely see some downside.
 
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