Can anyone document a catastrophic weapon failure with shooting 5.56 in a 223 or 223 in a 5.56?
It's not likely to blow up a gun in working condition. The typical effect if the tolerances stack up the wrong way is blown/pierced primers.
Here's some more information...
March 2010 Guns & Ammo
State of the Art by Patrick Sweeney
“Some of you may not have heard: The .223 and the 5.56 are not the same. If you ever asked, there will be someone at the gun club who will discount that. “Why, I’ve shot lots of 5.56 ammo in my .223, and I haven’t had any problems.” Well, I’ve taught police classes for years now, and we see those problems frequently, most occurring in the summer.
Rifles with .223 Remington-dimensioned chambers suffer from increased pressure when using 5.56 mil-spec ammo, and we’ll get blown primers when the sun is baking down."
September 2010 Guns Magazine
Up On ARs (Understanding Chambers Let’s clear our throats) by Glen Zediker
(Summarized from a photo caption: If you load two rounds with identical 80 gr bullets, one to engage the lands on a NATO chamber and the other to engage the lands on a SAAMI minimum .223 Remington chamber the OAL of the two rounds will differ by more than 0.150”)
SAAMI commercial .223 Remington specs call for a considerably shorter leade than NATO specs. A shorter leade raises pressures. Compounding this, NATO-spec ammunition is nearly always loaded to higher pressures than commercial .223. Shooting 5.56mm mil-spec ammo in a SAAMI “minimum” .223 Remington chamber can increase chamber pressure 15,000 psi, or more. ... If loads were worked up in a rifle with a NATO chamber ... they will be over-pressure if used in a SAAMI chamber.
http://www.saami.org/Unsafe_Combinations.cfm
In Rifle Chambered For: ----
Do Not Use These Cartridges
223 Remington ---- 5.56mm Military, 222 Remington, 30 Carbine
http://www.winchester.com/lawenforcement/news/newsview.aspx?storyid=11
(Link no longer works)
223 Rem VS 5.56mm
There are a lot of questions about these two cartridges. Many people think they are identical - merely different designations for commercial and military. The truth is that, although somewhat similar, they are not the same and you should know the differences before buying either cartridge.
* The cartridge casings for both calibers have basically the same length and exterior dimensions.
* The 5.56 round, loaded to Military Specification, typically has higher velocity and chamber pressure than the .223 Rem.
* The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.
* The 5.56mm and .223 Rem chambers are nearly identical. The difference is in the "Leade". Leade is defined as the portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. It is also more commonly known as the throat. Leade in a .223 Rem chamber is usually .085". In a 5.56mm chamber the leade is typically .162", or almost twice as much as in the 223 Rem chamber.
* You can fire .223 Rem cartridges in 5.56mm chambers with this longer leade, but you will generally have a slight loss in accuracy and velocity over firing the .223 round in the chamber with the shorter leade it was designed for.
* Problems may occur when firing the higher-pressure 5.56mm cartridge in a .223 chamber with its much shorter leade. It is generally known that shortening the leade can dramatically increase chamber pressure. In some cases, this higher pressure could result in primer pocket gas leaks, blown cartridge case heads and gun functioning issues.
* The 5.56mm military cartridge fired in a .223 Rem chamber is considered by SAAMI (Small Arm and Ammunition Manufacturers Institute) to be an unsafe ammunition combination.
http://www.fulton-armory.com/556-vs-223-Chambers.htm
Many NATO cartridges have bullets that will become jammed into the rifling of a SAAMI chambering (the throat is too short). This is VERY DANGEROUS....
Walter Kuleck, author of The AR-15 Complete Owner's Guide, says it can cause function and safety issues.
http://www.ar15barrels.com/data/223vs556.pdf
The big problem is that people often get away with it and therefore assume it must be a non-issue. Here are some reasons why people "dodge the bullet".
1. Some rifles marked .223 are, in reality, chambered and designed to safely fire 5.56 NATO. The Mini-14 (at least in the later models) is one of them, many of the AR style rifles are as well. If you contact the manufacturer they can provide that information.
2. Just because it's a bad idea doesn't mean that the gun will instantly explode. Guns are typically made with some safety margin built in. In this case some of the safety margin is being used to contain the extra pressure. That means that if something else goes wrong some of your safety margin will be otherwise engaged and a something that would normally be a non-issue could potentially result in a catastrophic incident.
The U.S. is not a C.I.P. regulated country and there is no similar proofing requirement in the U.S. We are regulated by SAAMI and the .223 SAAMI spec is 55,000psi. That means that firearms manufacturers in the U.S. can make .223 rifles to the .223 SAAMI pressure spec which is lower than the C.I.P .223 spec or the 5.56 NATO spec and can legally sell them without proof firing them.
The bottom line is that the pressure specs are different and the chamber specs are different. The chamber specs alone can result in higher pressure if a 5.56 round is fired in a .223 chamber. The combination of those two factors means that it's inadvisable to shoot 5.56 ammunition in a true .223 chamber, particularly if the gun is made by a SAAMI regulated manufacturer.
Stating that you haven’t heard of an incident and using that as a rationale for ignoring expert advice is not a sound way to approach dangerous situations. When experts tell you something is a bad idea, you don't do it anyway just because you haven't researched it carefully enough to find an incident that proves to you that they're telling the truth.
It’s irresponsible to disregard the advice of Winchester, SAAMI, Fulton Armory, et. al. simply based on opinion and the fact that you haven’t had trouble. YET....
Here are a few cases from the web...
http://www.glocktalk.com/forums/showpost.php?p=12080735&postcount=23
" I almost blew up my brand new Remington VS 223 the first time I shot it, shooting 55 grain Malayan ammo. It was way too hot for the rifle, and I first blew a primer, continued shooting like a moron, and blew the whole case head off."
<<Note that this is EXACTLY what Winchester's advisory above states could happen.>>
But, you say, “Malayan ammo?” Others shot the same ammo with no problems. Why do you suppose some people find that it works great in their guns while this guy (and others) state that they had blown primers and other even more serious issues? It could be ANYTHING other than an ammo/chamber mismatch, right? Especially if you refuse to believe that maybe Winchester, Fulton Armory, Glen Zediker, Walter Kuleck and SAAMI might know a little about ammunition and firearms.
Similarly I found other incidents with Lake City ammo which is generally known for quality. Reports of blown primers and extraction problems--with others stating that they were using the same lot of ammunition with no problems. Again, why does the ammo work well in some guns and not others? Differences in the chamber dimensions perhaps? Not if you just KNOW that Fulton Armory is trying to steer us all wrong, I guess...
http://www.familyfriendsfirearms.com/forum/archive/index.php/t-88006.html
Typically, in ARs it isn't dangerous, but .223 Remington chambers usually won't don't run well at all with 5.56mm NATO pressure ammo. The rifles will typically have failures to extract, blown primers, which will sometimes lock up the gun or make it not be able to fire. Sometimes that primer that's been blown out of the casing ends up under the trigger in the lower receiver and can keep the trigger from camming down when the shooter pulls the trigger to fire the rifle and the rifle won't fire.
http://tacticalunderground.us/forum/viewtopic.php?f=5&t=3305&start=20
Over at ZS, we had a fellow actually put it to the test. His rifle blew up.
Doing a search for "blown primers", surplus, and .223 will turn up a good number of additional incidents.
I found one online discussion where people were arguing back and forth about the quality of one particular flavor of surplus 5.56. Several kept saying it was great; very consistent and accurate, while others said they were having blown primers and extraction problems. Hmmm...what could that possibly be about?
Why do some folks get away with it? Face it, we don’t typically know the specific dimensions of the chambers in all the guns we shoot. As with the Mini, there are .223 stamped firearms that have 5.56 chambers to accomodate both flavors and the chamber variations are sufficient that if a manufacturer cuts their .223 chambers with a leade that's on the long side or if the particular flavor of surplus is not pushing the 5.56 OAL then there won't be a problem.
As Patrick Sweeney’s experiences demonstrate, this isn’t a HUGE mismatch, and in some cases it takes the slight extra pressure boost from shooting in warm temperatures to cause problems to show up.
In short, there are several ways that a person could "get away" with this inadvisable practice. On the other hand not everyone is so lucky.
I found several other experiences (and anyone who wants can almost certainly find more) that back up what the experts predict. So we have the advice of experts and the experiences of others to work from..
Looking through some of the incidents I found searching with the terms "blown primers", 'extraction', '223' and 'surplus', it's a bit funny and a bit sad. Nearly everyone blames everything except the one thing that the experts advise them of. They ignore the fact that the ammo works great in other guns and blame the blown primers and extraction problems on bad ammo.
http://www.dpmsinc.com/support/warning.aspx
DPMS recommends the use of high quality, domestically produced ammunition for best results and highest accuracy. For plinking and practice, we recommend only domestic, commercially manufactured ammunition.
...
The problem appears to be the bullet contour and the overall length of the cartridge, which is contacting the rifling before firing. <<leade length mismatch>> This is creating a gas port pressure and chamber pressure higher than recommended, therefore causing feeding and extraction problems...
This one is really amazing. DPMS actually figured out that there was a leade length mismatch (a known 5.56 in a 223 chamber issue), but they still chose to blame it on quality issues instead of noting the fact that they chamber their firearms for .223 and that using surplus 5.56 in a .223 chamber is known to cause exactly the problems they describe.
http://www.assaultweb.net/Forums/showpost.php?p=334408&postcount=15
Occaisionally some milsurp ammo in .223/5.56 can be too hot for hunting/target firearms. Some of the Chinese Norinco was a case in point and the pressure/blast was excessive for B/A sporters, [we had reports of blown primers, excessive fouling and jams.]
If you're willing to give the experts a bit of credence then the picture suddenly becomes very clear.
D), but I was under the impression those heavy bullets had a fatter ogive to get some of their weight (as opposed to simply being longer inside the case). If so, that fatter ogive will contact the lands sooner.
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