I am thinking of building my first AR using a kit from model 1 sales. My question is, on their website they list an option of 5.56 NATO or .223 chamber. Is there a difference? I was under the impression they were the same. I have no previous experience with this caliber, so thought I'd ask. Thanks, jdman

The .223 chamber is a bit "tighter".  

Get the 5.56 and you can shoot anything.

Like stick man said 5.56 is a bit looser.

5.56 is the nato designation with a slightly larger chamber so it can fire both .223 and 5.56.

Because of the slightly smaller dimension of the .223 chamber, pressures will build up higher and could be dangersous.  That is it generally.

Are there accuracy issues with the larger 5.56 chamber?  Thanks.

-YJ

all you need to know.

Ammo guide


there's alot there, but that's what was given to me when I asked the same question.  lots of helpful info there.


edit: added link

Quoted: I am thinking of building my first AR using a kit from model 1 sales. My question is, on their website they list an option of 5.56 NATO or .223 chamber. Is there a difference? I was under the impression they were the same. I have no previous experience with this caliber, so thought I'd ask. Thanks, jdman

DO NOT FIRE A 5.56 in a .223 chamber.  Not good for your health.

Get a 5.56 so you can shoot both without worrying about grabbing the wrong ammo at a group outing when folks have 5.56 and .223 on the table.

Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??  I think we're hearing a lot of 'urban legend' here, all of it without first hand experience.

Quoted: Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??  I think we're hearing a lot of 'urban legend' here, all of it without first hand experience.

If ya don't trust the Ammo Faq posted above, then I guess the warning from SAAMI won't make any difference to ya either: www.saami.org/unsafe3.htm.

Despite what YOU believe, there's good reason for not shooting 5.56 in a 223, but you should go ahead and do it, just to prove the experts wrong......

Mike

I've seen 5.56 jam up a .223 weapon, and I do mean "jam", not malfunction.  I've never seen it injure anyone, but I don't see the point in firing the wrong ammo regardless.....

Could always get a Wylde chamber and put your mind at ease.

Quoted: "Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??"

I don't, because I'm not stupid enough to do something like that " firsthand".   But you can go right ahead................  

Quoted: Could always get a Wylde chamber and put your mind at ease.

How does the Wylde chamber differ from the 5.56 since both will function with both .223 and 5.56?  Is the Wylde supposed to be more accurate than the 5.56?

-YJ

Quoted: Quoted: "Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??" I don't, because I'm not stupid enough to do something like that " firsthand".   But you can go right ahead................   hr

HAHAHA Yeah go right ahead.....just don't come shooting with me. I like to be accident free when I go and shoot! I don't think it'd be much fun having a gun blow up in your face.

Quoted: Quoted: Could always get a Wylde chamber and put your mind at ease. How does the Wylde chamber differ from the 5.56 since both will function with both .223 and 5.56?  Is the Wylde supposed to be more accurate than the 5.56? -YJ

The Wylde chamber is supposed to be a compromise between the tight chamber of the .223 and the looser 5.56 military.

Quoted: Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??  I think we're hearing a lot of 'urban legend' here, all of it without first hand experience.

Look, we are not slamming you on this.  It's just that you use the correct ammo with the correct firearm.  That is all.

What you have is a valid question, but why temp fate on such a dangerous question.  I'm sure many test have been ran in an controlled lab and have found the above statement to be true.  Plus you only get one opportunity to make a mistake with a firearm.

I think RRA uses Wylde chambered barrels and uppers. I haven't shot mine yet (in the mail), but I'm pretty sure it will be more accurate than I am (that's what everyone else who shoots RRA's says).

+1 on the Ammo FAQ.

Quoted: Does anyone know first hand that it creates a dangerous situation to shoot 5.56 in a .223 chamber??  I think we're hearing a lot of 'urban legend' here, all of it without first hand experience.

I tend to agree with rimfire here. There is a lot of talk about how dangerous it is but, no one has ever seen a catastrophic problem that can be narrowed to using 5.56 in a .223 chamber.
I personally have shot a whole lot of 5.56 through many different .223 chambers. This includes barrels of different composition and different 5.56 loaded rouns. I have used both M193 and M855 with 0 problems ever. I belive all of this talk started when one company put out a warning against using 5.56 in .223.    
Edit- I found this in Armalite's Tech notes:
"FACTS:

.223 Remington (SAAMI standard) and 5.56mm (NATO standard) rifle chambers are almost identical.  The difference is largely limited to the “freebore,” the cylindrical space in front of the case mouth, and the “lead” or “leade,” the the tapered region that eases the bullet into full engagement with the rifling.  NATO and SAAMI cartridges can normally be used interchangeably with no problem.

The SAAMI chamber features less freebore and a tighter leade, which normally provide better bullet fit and match-grade accuracy than the NATO chamber.  It is wonderfully suited to match bullets.  

Millions of rounds of NATO ammunition have been fired safely in Eagle Arms' and ArmaLite’s SAAMI chambers over the past 15 years.  Occasionally a non-standard round (of generally imported) ammunition will fit too tightly in the leade, and resistance to early bullet movement can cause elevated chamber pressures.  These pressures are revealed by overly flattened or powder stains that reveal gasses leaking around the primer.  

The first few rounds of ALL ammunition, from whatever source or lot, should be checked for pressure and other signs of defect before firing large quantities.  If you have a problem, you can generally bet that the ammunition meets neither SAAMI nor NATO specifications.

ArmaLite has adopted a practice of using a special, modified SAAMI chambers in its stainless steel match barrels.  This chamber is better for match use than the NATO chamber, but fires the NATO ammunition perfectly.  We use the NATO chamber in all moly (phosphated) and chrome-lined barrels.

ArmaLite’s larger AR-10® rifles are all chambered with 7.62mm NATO chambers.  .308 Winchester (SAAMI standard) ammunition functions perfectly in the 7.62mm chambers."


Stick with a good brand of 5.56- XM193 or LC.

JMO
Hispeedal2-Out.