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.223 or 5.56?

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Old 08-18-2011, 03:06 PM   #1
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Default .223 or 5.56?

Hi all,

I'm putting together my first AR and came across this conundrum, which I'm assuming is only a mystery to me since I can't find hardly anything on it. So the .223 and the 5.56 NATO seem to be the same round, and they look pretty much identical, but I read on this AR-15 upper receivers site that the 5.56 can take a .223, but not the other way around. Do I need to buy components that are made for 5.56 if I want my rifle to be more versatile, or is this a misconception? Are the two completely interchangeable?

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Old 08-18-2011, 03:27 PM   #2
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From my understanding you have one of 4 options.

1. Buy a .223 and shoot only .223 in it.

2. Buy a .223 Wylde which is set up for both .223 and 5.56

3. Buy a 5.56 which will run both .223 and 5.56

4. Buy 2 uppers for whatever you feel like shooting

The difference between #2 and #3 is with the Wylde barrel the rifling starts before it normally would on a 5.56 to try and get more accuracy with both the .223 and 5.56. Whereas if you buy a 5.56 the .223 may not be as accurate.

The reason for the difference is a matter of pressure, the 5.56 has more pressure than the .223 so if you fire 5.56 in a .223 it can cause premature wear.

This is my understanding of the subject I am sure that others will chime in with more detail and probably correct me where I was wrong.
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Old 08-18-2011, 03:32 PM   #3
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If you are building a general purpose or a fighting gun, you want a barrel with a 5.56 NATO chamber. If you are building a match grade rifle, you may want to consider a barrel with a .223 Remington chamber.

.223 Remington chambers are tighter than 5.56 NATO chambers, and 5.56 ammunition will not reliably feed in a .223 chamber. .223 Remington ammunition will feed without issue in a 5.56 NATO chamber.

You may also come across hybrid chambers like .223 Wylde. The .223 Wylde chamber was designed as a match chambering for semi-automatic rifles, and will accomodate both .223 Rem and 5.56mm NATO ammunition. It is relieved in the case body to aid in extraction and features a shorter throat for improved accuracy.
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Old 08-18-2011, 03:33 PM   #4
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The physical difference that I know of between the 5.56 and the .223 is the 5.56 has a different shoulder angle than the .233.
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Old 08-18-2011, 04:30 PM   #5
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The only reason to pick 556 over wylde is to shoot military tracers. I wouldnt go out of my way paying more just to get a wylde over 556.

If you plan on shooting steel ammo go 556 with chrome chamber.

People who are concerned greatly with accuracy tend to hand load rounds to fit their guns exactly
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