5.56 vs. .223??

J

Jeff Thomas

New member
Noted this recent comment in another thread:
Bushmasters come with a chrome-lined barrel,and a chamber designed for 5.56x45mm. Armalite barrels are unlined and I believe they are chambered for .223, which uses a cartridge case of a slightly smaller diameter. You can shoot either cartridge in both rifles ...
Click to expand...

I've always heard .223 Rem and 5.56 referred to as identical cartridges. Was the writer simply mistaken, or is this a nuance that I've missed along the way? [and, I'm asking an honest question here ... I mean no offense.]

Thanks. Regards from AZ
 
Same thing.
They are exactly the same thing.
.223 Remington is what the Military took and renamed 5.56MM for Nato purposes.
5.56x45mm is the Nato designation because guys in France don't now what a .223 Remington is.
 
There will always be somebody in the peanut gallery to...

quickly run up with their slide rule and pocket protector to straighten you out on the above. Same thing with ones who say 7.62 Nato is different from 308 Winchester. Purely semantic BS.

If anything, a military chamber would tend to be on the larger size of normal specs so it could chamber anything it came across, dirty or otherwise. A commercial chamber might be a little tighter, but still within max-min specs.
 
That is interesting.

Yes … of course they are the same round; however, 5.56mm and .223” are not the same measurement. I just pulled out a round and measured it using my micrometer and it reads .2245” (that’s 5.7mm).

Who names these things and by what rhyme or reason?
 
Good question, Scott.

Actually .223 is the designation chosen by Remington to differentiate it from the .222 and .222 Rem Magnums. All use a .224 diameter bullet despite the names. Similarly, the 38 Special and 38 Super all actually use 355-.357 bullets.

The commercial mfrs name things to appeal to buyers, just like car makers name their products after fish, animals, and ships. Marlin, Barracuda, Cougar, Mustang, Corvette. There is not necessarily any logical connection between the name and the actual thing. The Chevy 396 engine actually has 402 cubic inches, but 396 sounded more appealing. Go figure!
 
I've wondered why they chose 5.56mm as the designation for the round. 5.56mm is .219", .224 is 5.69mm and .223" is 5.66mm. What, were those 2 numbers already taken? (I already know the answer, they weren't.) Whose in charge of this name game?
 
Thanks ... I thought they were identical, but sometimes I am surprised.

Via TFL, I had learned in the past that different calibers aren't necessarily different calibers. Interesting fact there.

Regards from AZ
 
I agree with you Scott. It's funny how labels are placed upon certain calibers and they do not match the measurements. Another example is the .50 Action Express. It actually measures .495. I guess .50 sounds better then .49 Same applies with the .44 Cal (.430) etc etc :)
 
i think i've seen this question asked before at AR15.com. 5.56 is different from .223,.. 5.56 chamber will feed both 5.56 & .223,.. but .223 chamber is tight for a 5.56.

------------------------------------------------------------
Bushmasters come with a chrome-lined barrel,and a chamber designed for 5.56x45mm. Armalite barrels are unlined and I believe they are chambered for .223, which uses a cartridge case of a slightly smaller diameter. You can shoot either cartridge in both rifles ...
------------------------------------------------------------

hhhmmm,... i have an Armalite M15A4,.. it's chrome-lined. if you check Armalite webpage,.. their barrels are chrome-lined. and their rifles will chamber both .223 & 5.56,.. it's the national match barrels that are chambered for .223.
 
I just pulled out some Black Hills 77 gr. HP Match MOLY. A friend of mine who shoots for the Marine Corps Rifle Team left a box of this (his favorite load).

It mics. Right at .223”

What is deal? What are the actual manf. Specs on this round?
 
i dont want to offend you george, but i beleive the military cam out with the 5.56 mm first, and as always, the civillian shooting market found it in demand, so remington started chambering it as the .223 remington.
 
Sorry about the misinformation. Unintentional, and embarassing. I am sure I saw comparative specs on the two cartridges on the net somewhere,and they were different. If I can find it again, I will post it.
 
Chesty - I may be right - I may be wrong...
Doesnt really matter on this count... The two are the same thing. Same with 9mm Luger and 9mm Parabellum. Its the same thing.
They function the same and work in the same guns.

Now you guys are going to tell me the Plymouth Neon and the Dodge Neon are different cars.
 
Correct me if I'm wrong...

As I understand it, it's not the cartridges that are different, but the chambers that are different...

As for the cartridge's origin, work was being done on it by Remington in the late 1950s.

It was adopted by the military in 1964, and was introduced commercially by Remington in either late that year or sometime in 1965.

As for the seeming disparity in dimensions, isn't the rifling for this round .223/.224 across the grooves, and .219 across the lands?
 
According to Cartridges Of The World, SAAMI stated that 5.56x45mm military chambers and throats are different from .223 Rem. commercial chambers; hence, military ammo may produce high pressures in sporting rifles.

Now I have no personal knowledge of any problems resulting from firing surplus ammo in civilian rifles, but is this warning to be taken seriously or not?
 
CAUTION!

5.56 mm NATO ammo should only be fired in a rifle specifically chambered for it. This precludes the use of it in Kimbers (listed on the manual), other bolt action rifles and any rifle not explicitly stamped.

Only a few commercial rifles are capable of using 5.56, namely the Ruger Mini 14, Colt Sporter and variants of same brand and a few clones of the AR15.

This difference is enough to cause problems, most notably in reloading. Rounds produced to .223 Remington standards should not be reloaded for use in rifles chambered for 5.56.

.223 Remington can be used in a 5.56 but not the other way around.

See SAAMI for further info.
 
man this thread and glock vs 1911 are ole friends on TFL
;)
i did a few posts last round in July
http://www.thefiringline.com/forums/showthread.php?threadid=15031

heres some SAAMI datum
TECHNICAL DATA SHEET http://www.saami.org/unsafe3.htm
UNSAFE ARMS AND AMMUNITION COMBINATIONS

Ammunition used in a firearm must be the same caliber or gauge as that marked on the firearm by
its manufacturer. If the firearm is not marked as to the caliber or gauge, or if it appears that the
original marking has been overprinted or changed, it is the responsibility of the gun user to have a
qualified person determine what cartridge or shell can be safely used in the firearm.

The firing of a cartridge or shell other than that for which the firearm is chambered can result in the
cartridge or shell rupturing and releasing high pressure gas that can damage or destroy the firearm
and kill or seriously injure the shooter and persons nearby.

There are countless combinations of specific cartridges and firearms which are unsafe. Many of
these unsafe combinations are recognizable because of specific differences between the similar
chamber and cartridge dimensions. It is not possible to list every unsafe combination; therefore, in
the interest of safety, use only the cartridge (or shell) designated by the firearm or ammunition
manufacturer for use in a specific firearm. The cartridge caliber or shotshell gauge must be marked
on the firearm frame, receiver or barrel by its manufacturer.

The practice of rechambering firearms is not guided by industry standards. It is possible that a
firearm which has been rechambered may not be rechambered properly or the rechambered caliber
may not be marked on the firearm. The firearm user is responsible to find out from a qualified
person the cartridge caliber or shell gauge for which the firearm has been rechambered.

CENTERFIRE RIFLE
In Rifle Chambered For
223 Remington
Do Not Use These Cartridges
5.56mm Military


The Ammo have similar dimensions but different pressures and the chamers have different tolerence
 
My first .223 was one of the earliest Mini-14s produced. Bought it sometime before July 4th, 1976(?), I believe. (Had some visiting Russian profs from UT out for a July 4th barbecue; did some shooting and then went into town for the celebratory fireworks.)

Anyway, I shot any ammo I ran across, including GI. I never had a problem. None. Until TFL, I never even *heard* of a problem.

Now, as had been said umpteen dozen times before, GI brass is thicker-walled than civilian brass. If one loads to data-book maxima for civilian brass when using GI brass, there most likely will be a pressure-problem. Same with '06 and .308.

$0.02, Art
 
Fascinating. Now, we're back to these cartridges being different. And, it sounds like there is documentation to support that position.

As an aside, I just looked up 'Cartridges of the World', and they show it in their 'Home & Garden' category. Cute. ;) Perhaps Amazon.Com sees self defense as a normal part of home life? ;)

Thanks again for some interesting info. This one wasn't even on my radar.

Regards from AZ
 
Differing view on brass

I have sectioned and weighed many different type of 5.56/.223 Remington cases and have never found any difference in wall thickness/case volume that relates to the type of case. Matter of fact, I have found Federal American Eagle brass to have the highest weight of any domestic .223/5.56 ammo produced. It has very thick walls and a weak web, causing it the shed primers if reloaded when fired in AR15 type rifles.

The warning of arsenal brass and reloading does not apply to 5.56 unless there are some foreign produced rounds with execptionally heavy brass weights.

The idea of using water to determine case volume is less accurate than just weighing cases. Cases are formed based on outside dimensions with only minor variations possible in the extractor groove. Furthermore, brass is much more dense than water, making it a more sensitive parameter on case volume.
 
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