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I was reading somewhere that there is a difference between the two. I have always thought that they were the same as ammo I buy for my AR has 5.56x45(.223 Remington) on the label. Are they the same or different? Can one screw up my rifle?

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Simian

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5.56 is NATO and/or Mil Spec and has a thicker case.

.223 is commercial and is sized in SAMMII specs (Spelling?)

Some tight chamber match barrels in .223 can have problems with Mil Spec or 5.56 stuff.

Hope that makes sence.

Karsten
 

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Dear Karsten, Thank you for the information. One is constantly learning new things here. Would you also happen to know if there is a reason for the case being thicker? Or is it just a case of two different committees deciding upon different specifications? Thanks again and stay safe. Gary

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"I knew a man that I did not care for. And then one day this man payed me a call. We sat and talked about things on our mind. Now this man he is a friend of mine" Friend and Lover "Reach Out in the Darkness"
 

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Gary....As for why, why does to Guberment pay $300 for a hammer we can buy at HD.

Why pay more for thicker brass that is intended to get used once?

I will offer this from another board and hope that helps.

This is also why I buy Bushmaster's, they are one of the only Mil Spec out there chambered in 5.56 Nato

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This next one comes from Winchester: http://www.winchester.com/law/news/news.eye?storyid=11


quote:
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.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 East Alton Illinois


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Karsten


[This message has been edited by Karsten (edited 12-04-2001).]
 

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I think Professional Ord. originally reamed chambers to .223, hence a lot of problems. I had a type 97 pistol that ripped case heads off. My type 19 pistol (6 mos old) has no such problem as I believe they go with 5.56 chamber now.
 

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"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."

It pays to find out if your gun's chamber is cut to mil spec or SAAMI specs; I believe some such as the Ruger Mini 14 are cut to mil spec.
 
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