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Old School

5.56 NATO In .223 Rem Big NO NO!

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Most of you guys know enough not to shoot 5.56 in a 223 chamber but I just want to share.

 

In an effort to achieve max accuracy I'm working on max cartridge length In my 223 Rem heavy AR

 

So I make dummy loads with bullets hanging out and push them in to the chamber to see how long I can hang out the bullet.

 

Well...I decided to do the same thing with one of my 5.56 NATO chambers

 

HOLT SH!T Yes I know the differences in chamber dimensions, I can read...

 

But on my rifles there is .110" (measured with my half assed method) difference in free bore.

 

Well what is the consequence? 5.56 relies in massive pressure drop allowed by the free bore

 

So a NATO round fire in a 223 Rem chamber is subjected to a massive pressure spike as the bullet hits the lands.

 

Just thought I'd share.

 

When you're told not to shoot NATO 5.56 in a 223 Rem it's no BS.

 

On another note I'm impressed with AR design.

 

All rifles have unsupported chambers to some degree. But working on the AR, the amount of NON-support is the least I have ever seen..

 

OS

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I'll be honest. What you say is true. This is, as you noted, is nothing new. And you are just reiterating. I don't doubt you, or others either. But I must ask, have you, or has anyone, personally seen, personal know of, or even heard of, any instance of someone damaging (or worse!) a rifle chambered in .223 while shooting 5.56 in it?

 

I have seen and read thousands of posts, in probably hundreds of different threads, forums, or settings, about not to shoot 5.56 in a .223 chambered rifle, but have never actually read or heard of an actual example of a major issue. Now, I'm not saying that it hasn't happened, or it doesn't exist. I'd imagine it has (or else this discussion would be pretty funny wouldn't it!), I certainly couldn't have possible heard about everything. But really, is this issue a real one? Or does it just seem like one on paper?

 

Honest question. Like I said, I don't doubt it, I just have never heard of a real issue as a matter of fact. I also haven't tried it myself.

 

:p

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I have a suggestion or question. Couldn't you just take a 5.56 bullet and see if it will fall through a .223 barrel ?

Seems simple enought to me. Since it's .110 bigger - It's not going to fit and drop out the other end.. right?

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I have a suggestion or question. Couldn't you just take a 5.56 bullet and see if it will fall through a .223 barrel ?

Seems simple enought to me. Since it's .110 bigger - It's not going to fit and drop out the other end.. right?

 

Its not bullet diameter but freebore in the chamber.

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I'll be honest. What you say is true. This is, as you noted, is nothing new. And you are just reiterating. I don't doubt you, or others either. But I must ask, have you, or has anyone, personally seen, personal know of, or even heard of, any instance of someone damaging (or worse!) a rifle chambered in .223 while shooting 5.56 in it?

 

I have seen and read thousands of posts, in probably hundreds of different threads, forums, or settings, about not to shoot 5.56 in a .223 chambered rifle, but have never actually read or heard of an actual example of a major issue. Now, I'm not saying that it hasn't happened, or it doesn't exist. I'd imagine it has (or else this discussion would be pretty funny wouldn't it!), I certainly couldn't have possible heard about everything. But really, is this issue a real one? Or does it just seem like one on paper?

 

Honest question. Like I said, I don't doubt it, I just have never heard of a real issue as a matter of fact. I also haven't tried it myself.

 

:p

 

I recognize your doubt. But let me say I don't want to be the test victim.

And I won't load to standards that would result in spike like I would expect and I'm not afraid to push the envelope, really.

My hunting load for 30-06 were 150 gr bullets approaching 3000fps, just short of there.

But all scaled, couple for sight in and a couple for hunting. not a steady diet...

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Does anyone have input on a .223 Wylde chamber? I heard those were capable of handling 5.56. I don't have one at hand to mic, but it's hopefully coming in May. I concur from my research that dropping the hammer on a 5.56 in a .223 chamber increases pressures dramatically possibly causing abnormal wear or catastrophic failure. Never quite understood the cause till now.

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I have personally jammed 5.56 NATO in a 223 Rem chamber. I wouldn't call it damaged but I didn't try to force it into battery and fire it either.

 

This was a minimum spec chamber for a match 223 Remington Ar15 from bushmaster

 

 

Sent from my iPad using Tapatalk HD

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I have personally jammed 5.56 NATO in a 223 Rem chamber. I wouldn't call it damaged but I didn't try to force it into battery and fire it either.

 

This was a minimum spec chamber for a match 223 Remington Ar15 from bushmaster

 

 

Sent from my iPad using Tapatalk HD

 

So you didn't fire it?

 

Sure it'll fit just fine. And a match chamber would be the worst senerio..

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No firing. I've seen handguns that exploded due to stuck objects in the barrel. I didn't want to be the test case. My guess is that it would fired but been over pressure with sticky extraction but we'll never know.

 

 

Sent from my iPad using Tapatalk HD

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I completely agree with old school here.

 

BUT, I suspect the reason you don't hear about failures is a lot is pretty simple, the AR is sufficiently overbuilt, if you look at how much metal is around the chamber the odds of blowing it up with 5.56 pressures (or indeed OVER 5.56 pressures because the shorter freebore will result in even higher pressures) will probably not blow up most guns. It will most likely result in stuck cases, prematurely worn bolts, sheared bolt lugs, pierced primers and bolt face erosion, etc.

 

This doesn't mean you should it, it means you really really shouldn't, don't rely on the excess margin, it is only there to prevent catastrophic failure.

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I completely agree with old school here.

 

BUT, I suspect the reason you don't hear about failures is a lot is pretty simple, the AR is sufficiently overbuilt, if you look at how much metal is around the chamber the odds of blowing it up with 5.56 pressures (or indeed OVER 5.56 pressures because the shorter freebore will result in even higher pressures) will probably not blow up most guns. It will most likely result in stuck cases, prematurely worn bolts, sheared bolt lugs, pierced primers and bolt face erosion, etc.

 

This doesn't mean you should it, it means you really really shouldn't, don't rely on the excess margin, it is only there to prevent catastrophic failure.

 

To your point exactly Vlad. There is so little unsupported chamber and a bolt head that encloses the cartridge head it's pretty over built.

 

And yes the over pressure indications you described are what I would expect as well.

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There is not going to be a catostrophic failure on a single shot of a .556 round through a .223 chambered gun. The entire round is the same dimension in both calibers but the .223 projectile sticks out a teeny weeny bit further in the casing. In guns chambered for .223 the rifling starts a teeny weeny bit further back in the bore. Fire several hundred or thousand .556 rounds through it and you can cause stress and potentially fractures in the beginning portion or the bore before the rifling starts.

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There is not going to be a catostrophic failure on a single shot of a .556 round through a .223 chambered gun. Much too absolute of a statement.

 

The entire round is the same dimension in both calibers but the .223 projectile sticks out a teeny weeny bit further in the casing. In guns chambered for .223 the rifling starts a teeny weeny bit further back in the bore.There is a difference in dimensions for sure and a tiny bit? Tiny bits are what we deal with in dimensions so that is significant

 

 

Fire several hundred or thousand .556 rounds through it and you can cause stress and potentially fractures in the beginning portion or the bore before the rifling starts. Again this is a WAG and you don't really know the consequence.

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On the Saiga Forums I have read that the Saiga 223 is a misnomer. It really is chambered in 5.56.* Additionally, if I were ever going to have to shoot 5.56 in a 223 chamber, it would be in an AK, whose loose tolerances make for excellent reliability.

 

 

* - Please do verify this with the manufacturer or importer. Internet info is often worth what is paid for it.

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OK, here's the deal. The ar-15 is designed to eat proof loads without catastrophic failure. .223 rifles are engineered to eat .223 proof loads without catastrophic failure. Because of the way the government specs the proof loads for 5.56, the pressures for both the .223 proof load and the 5.56 proof load are essentially the same despite the max pressure for in spec ammo being different.

 

You are not talking blow your gun up kinds of pressure differences unless their are radical defects in the design or materials of barrel, bolt, and/or lockup of those two. What you will see if you have a bad match are things like hard to extract brass, primers popping out and getting in your fire control group, and brass so stuck that you rip the case head off trying to extract it. You will also get more stress on your bolt lugs, which means premature wear, and if it is a softer bolt, possibly significnatly less time before you crack and sheer one of the lugs. You won't sheer all of them at once, and they will crack first, so you will have warning. You will also bump up the pressure, which will erode the throat of the chamber faster, and probably can even cause gas port erosion to speed up (at least relative to a diet of .223). Heck, you'll probably get warning signs even earlier than that of excessive gas being blown back in yoru face as if you were using a suppressor.

 

Why shouldn't you lose sleep over this? Because you have ZERO idea what the actual dimensions of your chamber are unless you know what reamer was used, and how worn it was. Between all the variations in each of .223, .223 wylde, 5.56, 5.56 sam-r, noveske match mod0, etc. Look at the specs for them and they overlap all over the place. You'll find .223 reamers that are more generous than some 5.56 reamers. You'll find reamers that trade off freebbore length for freebore diameter, and leade length fro leade angle, etc. There is just not much you can do about it, and you'll get plenty of warning signs. So check your gear, and don't continue to run ammo your gun has problems digesting.

 

This is not like double charging a pistol cartridge, or even worse, filling a rifle cartridge with pistol powder. You are talking a 10% or less increase in pressure in a situation where stuff is engineered to survive at least 125% of specified pressure. The brass will fail first.

 

Here's an article with some chamber cutter specs and some pressure graphs of various ammo in various chambers. http://www.luckygunner.com/labs/5-56-vs-223/

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I was just talking to some people about this very topic last night. I bought a CZ527 in .223 and was wondering if 5.56 was useable in it or not. I did not take the gun home yet so I have not seen the manual for it. I saw nothing on CZ's website about NOT using 5.56 in the gun either, but that doesn't mean I am going to try it either.

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Good article.  It looks like I can use 7.62x51 in my .308 bolt action rifle (but you can't use .308 in a 7.62 rifle)

 

Everything i've been able to find so far says that even though my LWRC RERP is chambered in 7.62x51 is can handle either round interchangeably and so can almost all new "modern battle rifles". I'm still researching a bit more before i continue to use .308's in it.

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