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You sayin' it like you never seen 5.56 case stuck in 5.56 chamber
But never a 223!
There is no difference between the two. None. Its all lies propagated by the firearms and ammunition manufacturers.
Almost a quarter of a century ago, SAAMI recognized potential problems with shooters assuming that the 5.56mm cartridge was identical to the commercially available .223 Remington round. Here is their 31 January 1979 release, with some minor errors corrected:
With the appearance of full metal jacket military 5.56 ammunition on the commercial Market, it has come to the attention of the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) that the use of military 5.56mm ammunition in sporting rifles chambered for Caliber .223 Remington cartridges can lead to higher-than-normal chamber pressures and possible hazards for the firearm, its user and bystanders.
Tests have confirmed that chamber pressures in a sporting rifle may be significantly higher in the same gun when using military 5.56mm ammunition rather than commercially loaded Caliber .223 Remington cartridges, according to SAAMI.
SAAMI points out that chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber.
SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer.
In Rifle Chambered For Do Not Use These Cartridges
223 Remington 5.56mm Military
222 Remington
30 Carbine Additionally, SAAMI's Unsafe Arms and Ammunition Combinations Technical Data Sheet page states:
The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.
The .223 Remington and the 5.56mm NATO, when checked with a chamber ream from a reliable manufacturer of each, also have discernable differences in the areas of freebore diameter, freebore length (leade) and angle of the throat.
SAAMI
Technical Office:
P.O. Box 338
Branford
CT 06405-0338 (Ironically, given the nature of the on-line confusion exhibited by .30 caliber shooters, no similar SAAMI advisory is given concerning 7.62 NATO beyond the fact that those who have rifles chambered in "308 Winchester" shouldn't attempt to shoot cartridges marked "7.62x39" or "300 Savage." Well, duh!)
However, the estimable Clint McKee of Fulton Armory, has thoughtfully provided a brief monograph, The difference between 5.56mm and .223 Remington chambers in the AR-15®-type rifle, which explains this issue in greater (but quite readable) detail.
Olin's Winchester Ammunition site, in 2001, addressed this matter as well, in a concise monograph by Paul Nowak, and Randall Rausch has a number of excellent technical documents, with graphics displaying the differences between the two cartridges, available at AR15barrels.com. Of particular interest are headspace and reamer dimensions.
Further Views on "Differences"
At the October 2001 IALEFI Conference in Reno, Nevada, Giles Stock, retired from Phoenix Police Department after 20 years service, discussed the differences between the .223 Remington/SAAMI and 5.56mm/NATO rifle chambers. The long-time range master for handgun, rifle, carbine and shotgun at Gunsite and developer of the acclaimed Giles Tactical Sling suggested that, as a general rule, recreational rifles have the former, and military rifles the latter… but there is some overlap, most notably in the popular Sturm Ruger Mini-14 which has been offered in both specifications!
NATO chambers have a long leade1. SAAMI chambers are tighter and have a short leade. SAAMI chambers are designed for increased accuracy, but will yield dangerously high pressures in guns using military ammunition and/or which are subject to high volume shooting. Under such high pressures, a primer may back out completely, drop into the action and cause the firearm to stop working.
It has been suggested that an autoloading rifle utilizing a SAAMI-spec chamber may increase risk of overpressure due to the tighter, shorter leade which retards the projectile somewhat as it is attempting to exit the case. Leave the SAMMI chambers to the a bolt action and single-shot rifles.
ArmaLite, not the original, but the Eagle Arms pretenders, has its own views on the subject.
Winchester "White Box" Confusion
This has been making American shooters nuts for a number of years now… particularly in the immediate aftermath of 11 September 2001 when there was a major run on 5.56mm ammunition. Winchester's "generic" or "budget" USA, or "white box," brand of ammunition actually has two different 55-grain FMJ rounds, and one has to look closely at the "small print" to discern the difference.
For openers, in addition to the ATK-operated Lake City plant2, Winchester is also a primary supplier of M193 to the U.S. military. That particular X223R1 round is commercially available in the white USA box product encoded "Q3131." What few realize is that Israeli Military Industries (IMI), the sole supplier of ammo to the Israeli Defense Force (IDF), also supplies their M193 as a subcontractor for Winchester; that round is often made available in the USA white boxes marked "Q3131A." By most reports, qualitatively, it is the same round and performs virtually the same as the home-grown variant.
1.- Leade is the distance the projectile of a chambered round must travel upon ignition before it enters the bore of a barrel. It is measured in thousandths of an inch, and is a datum of considerable interest to benchrest shooters.
2.- The government-owned, contractor-operated Lake City Army Ammunition Plant (LCAAP) in Independence, Missouri, is the largest (458 buildings on 3,935 acres) small-arms manufacturing plant in the world.
With the appearance of full metal jacket military 5.56 ammunition on the commercial Market, it has come to the attention of the Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) that the use of military 5.56mm ammunition in sporting rifles chambered for Caliber .223 Remington cartridges can lead to higher-than-normal chamber pressures and possible hazards for the firearm, its user and bystanders.
Tests have confirmed that chamber pressures in a sporting rifle may be significantly higher in the same gun when using military 5.56mm ammunition rather than commercially loaded Caliber .223 Remington cartridges, according to SAAMI.
SAAMI points out that chambers for military rifles have a different throat configuration than chambers for sporting firearms which, together with the full metal jacket of the military projectile, may account for the higher pressures which result when military ammunition is fired in a sporting chamber.
SAAMI recommends that a firearm be fired only with the cartridge for which it is specifically chambered by the manufacturer.
In Rifle Chambered For Do Not Use These Cartridges
223 Remington 5.56mm Military
222 Remington
30 Carbine Additionally, SAAMI's Unsafe Arms and Ammunition Combinations Technical Data Sheet page states:
The .223 Remington is rated for a maximum of 50,000 CUP while the 5.56mm is rated for 60,000 CUP. That extra 10,000 CUP is likely sufficient to cause a failure in a chamber that's only rated for the "sporting" .223 Remington.
The .223 Remington and the 5.56mm NATO, when checked with a chamber ream from a reliable manufacturer of each, also have discernable differences in the areas of freebore diameter, freebore length (leade) and angle of the throat.
SAAMI
Technical Office:
P.O. Box 338
Branford
CT 06405-0338 (Ironically, given the nature of the on-line confusion exhibited by .30 caliber shooters, no similar SAAMI advisory is given concerning 7.62 NATO beyond the fact that those who have rifles chambered in "308 Winchester" shouldn't attempt to shoot cartridges marked "7.62x39" or "300 Savage." Well, duh!)
However, the estimable Clint McKee of Fulton Armory, has thoughtfully provided a brief monograph, The difference between 5.56mm and .223 Remington chambers in the AR-15®-type rifle, which explains this issue in greater (but quite readable) detail.
Olin's Winchester Ammunition site, in 2001, addressed this matter as well, in a concise monograph by Paul Nowak, and Randall Rausch has a number of excellent technical documents, with graphics displaying the differences between the two cartridges, available at AR15barrels.com. Of particular interest are headspace and reamer dimensions.
Further Views on "Differences"
At the October 2001 IALEFI Conference in Reno, Nevada, Giles Stock, retired from Phoenix Police Department after 20 years service, discussed the differences between the .223 Remington/SAAMI and 5.56mm/NATO rifle chambers. The long-time range master for handgun, rifle, carbine and shotgun at Gunsite and developer of the acclaimed Giles Tactical Sling suggested that, as a general rule, recreational rifles have the former, and military rifles the latter… but there is some overlap, most notably in the popular Sturm Ruger Mini-14 which has been offered in both specifications!
NATO chambers have a long leade1. SAAMI chambers are tighter and have a short leade. SAAMI chambers are designed for increased accuracy, but will yield dangerously high pressures in guns using military ammunition and/or which are subject to high volume shooting. Under such high pressures, a primer may back out completely, drop into the action and cause the firearm to stop working.
It has been suggested that an autoloading rifle utilizing a SAAMI-spec chamber may increase risk of overpressure due to the tighter, shorter leade which retards the projectile somewhat as it is attempting to exit the case. Leave the SAMMI chambers to the a bolt action and single-shot rifles.
ArmaLite, not the original, but the Eagle Arms pretenders, has its own views on the subject.
Winchester "White Box" Confusion
This has been making American shooters nuts for a number of years now… particularly in the immediate aftermath of 11 September 2001 when there was a major run on 5.56mm ammunition. Winchester's "generic" or "budget" USA, or "white box," brand of ammunition actually has two different 55-grain FMJ rounds, and one has to look closely at the "small print" to discern the difference.
For openers, in addition to the ATK-operated Lake City plant2, Winchester is also a primary supplier of M193 to the U.S. military. That particular X223R1 round is commercially available in the white USA box product encoded "Q3131." What few realize is that Israeli Military Industries (IMI), the sole supplier of ammo to the Israeli Defense Force (IDF), also supplies their M193 as a subcontractor for Winchester; that round is often made available in the USA white boxes marked "Q3131A." By most reports, qualitatively, it is the same round and performs virtually the same as the home-grown variant.
1.- Leade is the distance the projectile of a chambered round must travel upon ignition before it enters the bore of a barrel. It is measured in thousandths of an inch, and is a datum of considerable interest to benchrest shooters.
2.- The government-owned, contractor-operated Lake City Army Ammunition Plant (LCAAP) in Independence, Missouri, is the largest (458 buildings on 3,935 acres) small-arms manufacturing plant in the world.
I read it all but i do not know why..
But really i do know why..
Is that little 223 so weak as to fail under 60,000 Copper units of pressure.
Well could be more if the 5.56 was loaded to 60k and then the tight chamber on top of that..
I would think there was some over built in the guns to protect from this...
When you start seeing primers come out and case heads flowing into the bolt face I would
think you are closer to 70k-80k cup
But really i do know why..
Is that little 223 so weak as to fail under 60,000 Copper units of pressure.
Well could be more if the 5.56 was loaded to 60k and then the tight chamber on top of that..
I would think there was some over built in the guns to protect from this...
When you start seeing primers come out and case heads flowing into the bolt face I would
think you are closer to 70k-80k cup
Here is my fact check.
1) 223 and 556 cartridges are identical; the only difference is rounded edges of the shoulder, which is generally ignored. The dies and castings are identical. 223 vs 556
2) 556 is not "thicker" or has "less water volume" than 223
There are some rather big variations from lot to lot with no indications of one way or another: http://www.6mmbr.com/223rem.html
3) 556 and 223 pressure rating is the same according C.I.P.
SAAMI doesn't have 556 data. SAAMI does not use the same method or sensor as NATO and C.I.P., therefore pressure rating cannot be compared. SAAMI warnings about 556 not being used in 223 firearms has to do with the fact that 556 is not a SAAMI standard even though it physically fits in SAAMI specified chamber.
Since muzzle velocity is basically a function of pressure - you can confirm that 62gn offerings of SAAMI 223 Remington ammunition is very close to M855; therefore it's safe to assume that operating pressures are the same (regardless of measuring process and equipment)
4) 556 and 223 chambers are slightly different, but the allowable error in manufacturing process of production firearms exceeds the negligible difference between the two.
http://www.luckygunner.com/labs/5-56-vs-223/ shows that 223 chambered firearm pressure fell in between the two 5.56s.
5) 556 leade is extra long and extra wide. I can see how that might cause some accuracy and velocity drop in 556 chambers, but it shouldn't equal to "excessive" pressure in properly machined 223 chamber. I can see how with rapid fire and no cleaning this can become a progressive problem - but that has to be addressed at "know your firearm" level.
6) If the quality of ammunition is unknown and/or the rifle is showing signs of excessive pressure - the issue should be addressed regardless of the markings on the barrel.
Considering that there are many more 5.56 NATO marked budget barrels on the market - I would expect more issues with those, not necessarily due to "type of chamber" but poor machining.
1) 223 and 556 cartridges are identical; the only difference is rounded edges of the shoulder, which is generally ignored. The dies and castings are identical. 223 vs 556
2) 556 is not "thicker" or has "less water volume" than 223
There are some rather big variations from lot to lot with no indications of one way or another: http://www.6mmbr.com/223rem.html
3) 556 and 223 pressure rating is the same according C.I.P.
SAAMI doesn't have 556 data. SAAMI does not use the same method or sensor as NATO and C.I.P., therefore pressure rating cannot be compared. SAAMI warnings about 556 not being used in 223 firearms has to do with the fact that 556 is not a SAAMI standard even though it physically fits in SAAMI specified chamber.
Since muzzle velocity is basically a function of pressure - you can confirm that 62gn offerings of SAAMI 223 Remington ammunition is very close to M855; therefore it's safe to assume that operating pressures are the same (regardless of measuring process and equipment)
4) 556 and 223 chambers are slightly different, but the allowable error in manufacturing process of production firearms exceeds the negligible difference between the two.
http://www.luckygunner.com/labs/5-56-vs-223/ shows that 223 chambered firearm pressure fell in between the two 5.56s.
5) 556 leade is extra long and extra wide. I can see how that might cause some accuracy and velocity drop in 556 chambers, but it shouldn't equal to "excessive" pressure in properly machined 223 chamber. I can see how with rapid fire and no cleaning this can become a progressive problem - but that has to be addressed at "know your firearm" level.
6) If the quality of ammunition is unknown and/or the rifle is showing signs of excessive pressure - the issue should be addressed regardless of the markings on the barrel.
Considering that there are many more 5.56 NATO marked budget barrels on the market - I would expect more issues with those, not necessarily due to "type of chamber" but poor machining.
Damn mo, this debate really got to you huh?
Look, the fact is they are different. How much so and if it even matters except in the lawyered up minds of the SAAMI folks is a craps shoot. Maybe good in these circumstances, probably bad in others. What is interesting, from a reloaders perspective is if they are the same round why doesnt SAAMI just say so? Just do there own tests of standardized military ammo.
If you are a reloader i suspect you might be interested in viewing the latest load data sheets from Ramshot regarding the difference between .223 and 5.56. They have two sets of data and the 5.56 data calls for higher weights of powder for a given projo compared to the .223 data. Their 5.56 data is supposed to be used in NATO chambers at less than 62,000 psi, whereas the .223 data is for less than 55,000 psi.
Look, the fact is they are different. How much so and if it even matters except in the lawyered up minds of the SAAMI folks is a craps shoot. Maybe good in these circumstances, probably bad in others. What is interesting, from a reloaders perspective is if they are the same round why doesnt SAAMI just say so? Just do there own tests of standardized military ammo.
If you are a reloader i suspect you might be interested in viewing the latest load data sheets from Ramshot regarding the difference between .223 and 5.56. They have two sets of data and the 5.56 data calls for higher weights of powder for a given projo compared to the .223 data. Their 5.56 data is supposed to be used in NATO chambers at less than 62,000 psi, whereas the .223 data is for less than 55,000 psi.
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