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9/22/2017 12:11:25 AM
Posted: 9/6/2010 9:24:40 AM EDT
I just picked up some 1X fired brass at the range from some guys shooting next to me stamped M193 and the other side 80 which I presume is the year. No other markings. They were shooting AR-15's. I believe it is 5.56mm but it does not say .5.56 or .223 on the case head. I have never loaded anything with this head stamp. Is it Nato spec? It's probably common knowledge but I have been shooting 30 cal. for many years. If one of you knowledgeable guy's would clue me in I would be thankfull. Thanks in advance.
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Link Posted: 9/6/2010 9:39:34 AM EDT
Does it have a cross in a circle on the headstamp? That's the NATO headstamp mark. If it does it was 5.56. But is there a differance in the brass between .223 and 5.56?
Link Posted: 9/6/2010 9:41:41 AM EDT
[Last Edit: 9/6/2010 9:48:41 AM EDT by The_Mad_Axeman]
The cases are Centurion .223, they claim to be mil spec, but I have yet to see how well they hold up to reloading.

The .223 and 5.56 cases are dimensionally the same on the outside. However, 5.56 cases tend to be thicker walled, so the internal capacity changes very slightly.
Link Posted: 9/6/2010 11:56:09 AM EDT
[Last Edit: 9/6/2010 11:56:24 AM EDT by WayOutWest]
Originally Posted By The_Mad_Axeman:

The .223 and 5.56 cases are not dimensionally the same on the outside. However, 5.56 cases tend to be thicker walled, so the internal capacity changes very slightly.


Link Posted: 9/6/2010 12:15:49 PM EDT
[Last Edit: 9/6/2010 12:22:15 PM EDT by 1Devildog]
Are you sure about the .223 and 5.56 cases being different dimensions and wall thicknesses? I could have sworn that the cases are identical and that the wall thickness attribute relates to 7.62x51mm military brass vs. commercial .308 Win. If you are referring to the American Rifleman article on reloading .223? I beleive the author's information regarding reduced case capacity with 5.56 brass was in error. The differences are in the chambers and velocity.

Federal has made some .223 brass with a thinner head in the area above the primer pocket, but not the web. I've sectioned and compared this Federal brass with Remington .223 and Lake City 5.56. Web thicknesses are the same.

Been reloading commercial and military .223 and 5.56 brass for years using the same data and can see no difference...

The only real difference I have seen between the two is that the case length tends to run shorter on .223.

As for the Centurion brass, the year should be read as "08" instead of "80".

Link Posted: 9/6/2010 12:39:41 PM EDT
The outside dimensions of .223 and 5.56mm cases ARE IDENTICAL. The difference is in the leade and freebore of the CHAMBERS. Further, GI 5.56mm cases are NOT thicker walled than civilian cases. In fact, IIRC, Lake City cases are relatively light, especially when compared to Lapua cases... I have just wasted 10 minutes looking for Molon's chart showing the weights of a variety of different brand cases, and his data clearly shows this.
Link Posted: 9/7/2010 7:56:15 AM EDT
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