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Discussion Starter #1
I seen a post on one of the forums with a link to the diffrences between the 2 does anyone have that link so I can read up on it.
 
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Discussion Starter #2
i would like to know as well.. i know one can shoot both.. but the other only that type...
 
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Discussion Starter #3
5.56 is loaded to different (usually hotter) specs. NATO and SAMMI use different chamber and pressure specs.

There is a small diffrence between the two types of brass also. 5.56 brass is thicker and if you reload affects case volume. If given the same powder charge, bullet, primer, ect. NATO brass will give you higher pressures compared to the thinner walled .223 brass.

There are also some minor differences between the two chambers as far as measurements go which can lead to problems.

www.ammo-oracle.com is where you need to go for the need to know info.

FYI-5.56 AND .223 are safe to shoot from 5.56 NATO chamber. However it IS NOT safe to fire 5.56 from a .223 chamber.
 
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Discussion Starter #6
I didnt get a barrel yet for my AR build so I really didnt even look into what most of them chamberd at? is the M855 safe to fire through a .223 chambered barrel? I see that cheaperthandirt has M855 surplus there its saying 5.56 and 223 so what is the M855 really made for?
 
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Discussion Starter #7
I didnt get a barrel yet for my AR build so I really didnt even look into what most of them chamberd at? is the M855 safe to fire through a .223 chambered barrel? I see that cheaperthandirt has M855 surplus there its saying 5.56 and 223 so what is the M855 really made for?
M885 is current issue NATO 5.56 ammo it IS NOT SAFE to fire through a .223 chamber. Just for diversity reason I suggest you get the barrel chambered for 5.56 then you are good to shoot both and be safe. When I go qual at the range I get issued M855 everyday and our issue rifles are 5.56 nato chambered.

Army Guy-yes you are correct firing 5.56 in a .223 chamber can cause unsafe chamber pressures.
 
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Discussion Starter #9
after reading that tho its saying that DPMS barrels are marked .223 but really measure 5.56. for the most part I was looking at DPMS for the rest of my build. when it comes time to get my barrel Ill just talk to the gun shop and let them know I plan an using 5.56 rounds in there and let him take care of it, I have 100 rounds of M855 on the way and if i get more money im going to order a case of it.
 
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Discussion Starter #11
Check with the weapon manufacurer, my ar is marked 5.56 so .223 & 5.56 are safe. My ranch rifle is marked .223 but the owners manual says .223 & nato 5.56 are safe. 5.56 ammo has a longer bullet ogive, which will affect pressure when fired in a .223 chamber.
 
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Discussion Starter #13
Would I be safe in assuming that most if not all AR manufacturer's do a 5.56 chamber?
Yes and no. If it is "varmint" barrel, target barrel, heavy barrel, anything designed for accuracy, it will generally be .223. The vast majority will be 5.56. There is also a Wylde chamber that mixes the two. a little tighter than a true 5.56, but still compatible with .223 without sacrificing as much accuracy.
 
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Discussion Starter #14
you can shoot a 223 in a 5.56 but you shouldnt shoot a 5.56 in a 223
223 chambers tend to be more accurate
 
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Discussion Starter #15
I was looking at rock river arms barrels and almost all of them are wylde witch will do eather or. now i just need to save 600 bucks for my complete upper.
 
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