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Discussion Starter #1
Hey there everyone, just joined the forum. I hope this question isn't a dumb one but I haven't got an answer for it. I know the difference between 223 & 5.56 but when I look to buy ammo online I often see the ammo lable listed as "223/556" so my question is which one is it? The ammo I have purchased online in the past was specifically listed as one or the other but I commonly see ammo sold as "223/556" so I'm not sure which one it actually is. Again I hope this isn't a dumb question but I am curious. Thanks and look forward to the replies.
 

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Galactic Effectuator
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The cartridges are dimensionally identical. The major difference is a slight difference in chamber dimension for one of them. This makes one of them dangerous to fire in the other due to potential pressure spikes.

Forgive me for not keeping better track of this, but I don't have anything chambered in either cartridge.

From the marking on the ammo box you report, one would understand it can be fired in either chamber. Which would logically suggest it is low pressured enough not to disturb anything in either chambering. Perhaps the 'fine print' on the box or the manufacturer's website could resolve your qualms?
 

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"........when I look to buy ammo online I often see the ammo lable listed as "223/556" so my question is which one is it?"

Not having. to my knowledge, any clairvoyants on this forum, I don't expect any answers that can clarify what is actually for sale by chambering at the other end of the "internet advertisement".

Give the advertiser a call to verify or ascertain the ammo "headstamping". Otherwise, be prepared for additional inputs in helping you guess.
 

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Discussion Starter #4
Thanks for the replies fellas. Yea my main concern is that I was looking at purchasing bulk reloads and the picture on the site was just a generic cardboard box that just says 223/556. I'll email the vendor and try and get some clarifications.
 

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Maybe this will make it easier. If your barrel is marked 5.56, you can shoot either.

So if you have a .223 barrel, you have to worry about 5.56, it fits, but you shouldn't

shoot it.
 

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Although the dimensions are almost identical , the .223 Remington and 5,56x45mm NATO still vary in maximum pressure and chamber sizes.

The maximum and average pressure of various types 5.56 mm NATO go above the maximum test pressure of the .223 Remington . The military extended the projectiles over the years, while the standard for .223 Remington remained the same , it is possible that 5,56x45mm NATO ammunition is not safe to use in weapons chambered for .223 Remington.

About the .223/.556 issue: Its simply the category name, the heading to cataloque, under which you can find both the .223 and the .556 ammo a dealer has to offer. A specific .223/.556 combined model in one cartridge doesn’t exist.

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223vs556-e1446155529154.jpg
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Regards
ARMARIN
 

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The cartridges are dimensionally identical.
Not quite. There is a small but noticeable difference. The neck is slightly longer on a 5.56. Off the top of my head i forget the length difference but comparing them side by side with a .223 it can be seen. You definitely notice it when trimming them mixed with .223 brass.
 

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I've wondered the same thing. Through my purchases, I've determined that when it says .223/5.56 it is actually a .223. Of you want 5.56, get the 5.56 NATO, that really is 5.56.
 

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Grand Imperial Poobah
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Thanks for the replies fellas. Yea my main concern is that I was looking at purchasing bulk reloads and the picture on the site was just a generic cardboard box that just says 223/556. I'll email the vendor and try and get some clarifications.
Just an FYI, be selective with where you get your reloads. I never buy reloads from an individual, unless I trust them with my life. I only buy reloads from a trusted source, such as, Freedom Munitions or Georgia Arms.
 

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I missed the part about them being reloads. I have never seen 5.56 available as a reload so i would bet they are .223. They could still use 5.56 brass when reloading though. Also what Mad said above!
 

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My mini 14 shoots both. Most AR 15 types only recommend .223.
Some have a special chamber that feeds both safely.

Sent from my XT1080 using Tapatalk
 

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RELOAD=More PEW PEW
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Not having an AR type yet, I appreciate that kind of thread, it makes me realise that when I do buy one I'll be sure the barrel will read 5.56
 

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Not having an AR type yet, I appreciate that kind of thread, it makes me realise that when I do buy one I'll be sure the barrel will read 5.56
When i was building mine i couldn't find one so i opted for a .223 but there is also the .223 wylde which is safe to shoot both. I couldn't find one because i had to get a non threaded standard barrel, I have shot some 5.56 through it but mostly run my .223 reloads in it. I still want to build another upper at some point and the barrels are easy to find now....or were a few weeks ago when i last checked but that's probably changing fast!
 

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There are many brands out there selling 5.56 in boxes that are marked 5.56 but they are not 5.56. They are .223. This is not the same round. The 5.56 NATO is also called XM193. There is only 1 company in the United States that is licensed to manufacture XM193. Unfortunately for reasons I can not fathom Federal is not enforcing its license as far as labeling goes. If you are buying American made ammo that is stamped 5.56 or XM193 and it is not made by Federal then you are buying .223.

This only applies to American manufactures of XM193. PMC for example is a Korean ammunition manufacturer and the 5.56 X-Tac is true XM193. Its good ammo but I prefer to buy American when ever I can. This narrows the choices down quite a bit. If you want the best performance from your 5.56 chambered AR-15 you buy Federal XM193 or PMC X-Tac. Federal is also slightly less expensive.
 
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