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Posted: 10/7/2003 6:49:11 AM EDT
[#1]
From my experience Colt and Bushmaster are chambered for 5.56. It is very rare that you will find a new barrel from either that the bolt will NOT lock up on a no-go 223 headspace gauge. However the bolt 'like it's supposed to' will not lock up on a 5.56 headspace gauge. Armalite which has 5.56 stamped on weapon is really chambered 223. A call to Armalite will confirm this. Now you may or may not run into problems using other barrels. A solution is to get a 5.56 reamer and make it a real 5.56. Not a hard thing to do. Good shooting
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Posted: 10/7/2003 10:15:41 AM EDT
[#2]
[url]ammo-oracle.com[/url]
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Posted: 10/7/2003 3:24:55 PM EDT
[#3]
???? I thought they were the same thing. Kind of like 7.62 X 51 (Nato) and .308 Winchester.
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Posted: 10/7/2003 3:38:47 PM EDT
[#4]
They are different just very slightly so.
I run 5.56mm out of one .223 chamber I have and have no ill effects... There have been some pressure concerns mentioned, I have yet to see any on my end. |
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Posted: 10/7/2003 5:58:35 PM EDT
[#5]
i SURE DON'T KNOW THE DIF IS EXCEPT ON THE HEAD STAMP. FROM ALL THE INFO I HAVE GLEANED OVER THE YEARS THERE IS NO DOF. THE 5.56 WAS USED FOR MILITARY, AND THE .223 WAS FOR COMMERCIAL AND ESPECIALY WHEN 5.56 WAS NOT ALLOWED TO BE SHIPPED OUT TO CERTAIN COUNTRYS AS WE WERE AT WAR AND MILITARY AMMO THAT KILLED POOR LITTLE VC WAS NOT POLITICALY CORRECT, HENCE THE .223. I THINK THAT SOME BARREL MAKERS ARE TRYING TO MAKE A FEW BUCKS OR THEY JUST DON'T KNOW THAT THERE IS NO REAL DIF.
GOOD SHOOTIN, JACK |
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Posted: 10/7/2003 8:10:59 PM EDT
[#6]
Quoted: They are different just very slightly so. O.K., then what are the case dimentions on the both of them? That would be the only difference I could think of... if there was one. Pressure's would change with the charge and possibly bullet weight. So don't make your claim based based off of M-whatever military loads. BTW, for my .02 I'd have to agree with 3rdtk |
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Posted: 10/7/2003 8:25:30 PM EDT
[#7]
[img]http://ammo-oracle.com/images/556cham.gif[/img]
[url]http://www.saami.org/unsafe3.htm[/url] Gee I guess I did not make it up... |
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Posted: 10/7/2003 9:13:12 PM EDT
[#8]
Quoted: ???? I thought they were the same thing. Kind of like 7.62 X 51 (Nato) and .308 Winchester. I'm pretty sure 7.62 NATO and .308 are not exactly the same either. You could probably find something on this at the SAAMI site too. |
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Posted: 10/8/2003 6:46:14 PM EDT
[#9]
Don't get me wrong here, I wasn't trying to bust anyone's balls over this... although looking at my reply it may have seemed that way. Sorry for any misunderstanding. Honestly!
I just wanted to see the numbers. They are just ever so slight. I can see how it would "work" but maybe not work as perfectly engineered if you interchanged the two. |
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Posted: 10/9/2003 12:03:27 AM EDT
[#10]
Quoted: Gee I guess I did not make it up... You didn't make it up Kev, there is a pretty neat engine [url=http://www.clymertool.com/cgi-bin/reamer.cgi?cmd=CMD_START&gunID=2&reamerID=7]here[/url] that calls up the dims for the .223 and 5.56. The dimensional differences are numerous. ekimnat, The same guys that make awesome rifle barrels also make awesome AR barrels. Prolly cuz ARs are, well....rifles. You're not, reliably, going to get "sniper grade" from a factory job. How accurate do you need a race rifle to be anyway? |
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Posted: 10/9/2003 5:36:26 AM EDT
[#11]
Arianboy, there is enough difference that Bushmaster makes a distinction between the two and makes its chambers exclusively in one set of dimensions. IIRC, they do 5.56mm (instead of .223) to avoid possible pressure excursions.
They even say this in their catalogs. Kevin B is spot-on here. v/r, Cruzado |
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Posted: 10/9/2003 6:29:23 AM EDT
[#12]
Normally, I use 223 ammo in my 5.56 barreled AR-15s but I never use 5.56 ammo in a 223 rifle (normally because my 223 varmint rifle likes better reloads).
I always thought the looser 5.56 had to do with the chamber of the rifle to allow a little more room to prevent malfunctions but the ammo was basically the same... What we have posted so far indicates that some 5.56 ammo is a little hotter and may be un-safe in a 223 chambered rifle... I would be interested in more specific details on the pressure curves and I am posting here so I can do a little "homework" when I get a chance. |
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Posted: 10/9/2003 7:29:07 AM EDT
[#13]
Note the diagram posted by KevinB: the 5.56 chamber allows the bullet to get a "running start" before it hits the rifling.
All other factors held equal, you end up with lower chamber pressures. The tighter .223 chamber with hotter 5.56 ammo? All bets are off unless you measure the actual pressure using a pressure barrel. I'm not saying you'll get a Kb!, just saying that you'll get an unknown increase in pressure. You could get a starting reference using factory .223 ammo against a .223 chambered rifle with a transducer epoxied to the barrel, but all this would tell you is how many percent greater pressure the 5.56 load was generating. You couldn't get absolute numbers. v/r, Cruzado |
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Posted: 10/9/2003 7:34:27 AM EDT
[#14]
So which rifles come in 223 and which in 5.56?
I am shopping for my first AR and want a 5.56mm. |
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Posted: 10/9/2003 8:04:31 AM EDT
[#15]
You know, I think you hit something that could be added to ... [url]ammo-oracle.com[/url]
As the article says, Bushmaster and Colt are 5.56 but beyond that I am not sure... RRA website doesn't say (Only 223/5.56 used) DPMS doesn't mention it Olympic Arms Ultra Match is 223, others barrels not defined Armalite is 223: [url=http://armalite.com/library/techNotes/tnote45.htm]See This!!![/url] Also note that Bushmaster DCM and Varmintmaster are both SAAMI (223) Kind of an interesting question now that I look! |
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Posted: 10/9/2003 8:59:36 AM EDT
[#16]
Interesting stuff, Q-bore. It says that firing hotter 5.56 ammo in a tight .223 match chamber can raise chamber pressures by up to 15,000 psi.
That could put you above the working pressure range of one of the new Winchester short magnums. I wouldn't want to stress any rifle like that regularly if it wasn't designed for it in the first place. I don't do my own handloading, but I know enough to know that if you have a custom match chamber with tighter dimensions, you'd better make a chamber cast and measure every dimension to make sure your handloads aren't resulting in the bullet ogive "biting" into the rifling before you've even pulled the trigger. v/r, Cruzado |
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Posted: 10/9/2003 12:37:11 PM EDT
[#17]
[img]photos.ar15.com/ImageGallery/Attachments/DownloadAttach.asp?iImageUnq=3425[/img]
-Troy |
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Posted: 10/9/2003 3:00:21 PM EDT
[#18]
Quoted: Quoted: ???? I thought they were the same thing. Kind of like 7.62 X 51 (Nato) and .308 Winchester. I'm pretty sure 7.62 NATO and .308 are not exactly the same either. You could probably find something on this at the SAAMI site too. Correct, they are different also; [url]www3.sympatico.ca/shooters/7_62vs308.htm[/url] |
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