5.56 vs .223 Question

[Kick]

I have a .223 DPMS AR-15. I am looking to stock up on ammo and I've noticed that 5.56 seems more readily available and therefore the prices are a little cheaper even with the bigger name manufactures.

I have heard different people say different things such as:

You can shoot .223 through a 5.56 but not the other way around.

The rounds are exactly the same.

And everything in between.

Can anyone tell me if they have any personal experiance putting 5.56 ammo through a .223 gun or if it is just a bad idea in general?

 

[cosermann]

5.56 NATO and .223 Rem. are not exactly the same.
.223 can safely be fired in a 5.56 NATO chamber - not (necessarily) the other way around.
Some AR mfgs are pretty good about stamping their barrels with the correct chamber information.
Some are more sloppy about it.
I don't recall how DPMS fits in off the top of my head.
I'd go by what DPMS tech support says.

From the DPMS web site FAQ:

"What chambers are used in DPMS AR15 barrels?
To determine the chamber of your DPMS barrel, look to the underside of the barrel forward of the gas block/front sight base for the chamber stamp. This stamp will give your rifle's actual chambering along with the twist rate of the barrel. DPMS currently produces barrels chambered in .204 Ruget, .223 Rem, 5.56x45mm, 6.8 SPC II, 7.62x39mm, .243 Win, .260 Rem, .308 Win, .338 Fed and 6.5 Creedmoor."

If it's stamped ".223 Rem" it could have a tighter chamber.

:: Ammo Oracle <<== According to the Ammo Oracle, "DPMS marks their barrels ".223", though they actually have 5.56 chambers." Hmm.

Send DPMS an email.

 

[aclark]

From So you want to buy an AR-15, huh? - Police Forums & Law Enforcement Forums @ Officer.com

That's about all I've read on it, I'm sure someone could give you more specifics.

The proper chambering for a fighting rifle is 5.56 NATO, not .223 REM. While the cartridges are identical to the naked eye, they ARE nonetheless different. Most importantly, the 5.56 round will not feed reliably in the tighter .223 REM chamber. If you are looking to buy a match rifle, look for .223 REM and buy/load for it specifically. If you want a fighting rifle, you want the looser 5.56 NATO chamber.

 

[schapm]

From another forum

Can you shoot a .223 in a 5.56 and vice versa?

Well, in short yeah you can. Are there issues with it, well maybe so..... Will it blow your gun aparts and send pieces of the gun thru your brain housine group, probably not. But lets take a look at what the issues are for reals.

First of all there are three major types of AR chambers. The .223 SAMMI, the .223 Wylde and the 5.56 NATO. It's all so crazy and convolutted that we will skip right to the point of it all and look at it in laymans terms.

The real issues are the case neck, freebore length, throat angle and headspace. Now what do they each mean?

Case neck- Thats where the bullet sits in the case.

Freebore length- Thats the length between cases end and where the lands and groove start. This is where the bullet is actually free in the bore when it leaves the case. This affects the pressure of the round as the lands and grooves cause pressure to build behind the bullet.

Throat angle- This is the angle of slope where the freebore ends and transitions into the lands and grooves.

Headspace- This is the depth of the chamber

Now the headspace on all chambers is the same at 1.4636, so that is a non issue. The throat angle is significantly different though, 3 degrees for the SAMMI and 1.25 degrees for the other two. How does this affect you? It makes the pressure in the SAMMI start quicker as pressure is appled more abruptly.

Freebore length is a big issue in the three. The freebore for the SAMMI is a mear .025, the Wylde is .062 and the 5.56 NATO is .057. What does that mean? It means that the SAMMI builds pressure a lot faster than the Wylde or NATO chambers. Add this to the fact that NATO rounds are already a few hundred feet per second faster and as much as 5,000 PSI higher in oressure and you have an issue building rapidly. As is the pressure.

Does this mean that your gun is going to explode by using NATO ammo in your .223, probably not. They are massively over engineered and generally pretty safe for these kinds of things. They are designed to take pressure spikes, however I DO NOT RECOMMEND IT. It simply is not safe. You WILL probably start to see primers popped out of the cases or swollen.

So what do we do about it all? Well, we try to order all of our AR's in the 5.56 chambers. That allows you to shoot whatever you want to in the gun. The next thing you can do is shoot .223 ammo in your guns. Milsurp is not as cheap as it used to be, so there is not much advantage to go that route anymore. But if you do find a deal having a 5.56 chamber is going to make life more comfortable for you. But if you dont have a 5.56 chamber, just dont shoot milsurp ammo.

 

[dtkw]

I have a DPMS AR15, on the barrel it says 5.56Nato/223.

 

[phil]

From what I understand (and I may be completely wrong) 556 has a much higher chamber pressure(?) than 223. This may cause a ka-boom if you use 556 in a 223 only gun.

All that being said...I have a friend that has a mini 14 and a .223 AK that he has fired probably 500 rnds of 556 through each with no malfunction....YET!

I would strongly recommend to feed your rifle what it is made to eat.

 

[pinshooter45]

More Pressure!

From what I understand (and I may be completely wrong) 556 has a much higher chamber pressure(?) than 223. This may cause a ka-boom if you use 556 in a 223 only gun.

All that being said...I have a friend that has a mini 14 and a .223 AK that he has fired probably 500 rnds of 556 through each with no malfunction....YET!

I would strongly recommend to feed your rifle what it is made to eat.

Yes 5.56 does develope more pressure, and that is why it will eventually damage a rifle chambered in .223. But it wont blow the gun up. Just a steady diet of 5.56 in .223 do internal damage to the chamber. plenty of info on internet did a bunch before I bought my Bushy, that's why I made sure it chambered 5.56. As I remeber Mini 14's originally were not designed for 5.56 and many were ruined by using surplus NATO ammo. And I don't think the Olympic Plinker will take 5.56, looked at a couple and it is only marked .223

 

[Kick]

Thanks everyone. Sounds like I should have been a member here and posted before I bought the .223.... Maybe I would have bought something chambered in 5.56...

 

[Kick]

I have a DPMS AR15, on the barrel it says 5.56Nato/223.

I have a buddy with one like that. He feeds his 5.56 with no problems, yet at least...

 

[Mr. Habib]

Thanks everyone. Sounds like I should have been a member here and posted before I bought the .223.... Maybe I would have bought something chambered in 5.56...

Some of the confusion comes from the way the military and SAAMI measure chamber pressure. SAAMI calls for a conformal transducer at the midpoint of the case. The military use a pizo transducer at the case mouth. These give different readings that are not interchangeable or directly correlated. My brother in law does ammo development for the military and has had test barrels with both transducers and has seen differences of 5-6kpsi from one method to the other. If you want to be safe you could have a gunsmith finish ream your barrel to 5.556x45, or buy a reamer and do it yourself.

 

[cosermann]

Thanks everyone. Sounds like I should have been a member here and posted before I bought the .223.... Maybe I would have bought something chambered in 5.56...

Well, don't be too sure until you contact DPMS with your serial number and ask them about your chamber. I think they were a little loose on their stampings in the past. IOW, some of the DPMS rifles that were stamped .223 had 5.56 chambers according to some. Bottom line, ask.

If you don't like the answer you get, you can always swap in a different barrel.

 

[Kick]

Well, don't be too sure until you contact DPMS with your serial number and ask them about your chamber. I think they were a little loose on their stampings in the past. IOW, some of the DPMS rifles that were stamped .223 had 5.56 chambers according to some. Bottom line, ask.

If you don't like the answer you get, you can always swap in a different barrel.

Thanks, I shot them an e-mail with my serial number. I'm kinda hoping that they did get a little loose with thier stamping... Kinda sad when you find yourself hoping that the factory made a mistake with your weapon!

 

[cosermann]

Well, mfgs do their best to please everyone. Not everyone wants a black rifle for the same reason. Some who use them chiefly for varmint hunting like the tighter chamber for example. Best wishes!

 

[hunter_47443]

Good to go

I just bought a DPMS 2 weeks ago.
Reading through here made a cold chill go through me & I just pulled my A-15 out of the case, turned it over and took a look at the underside of the barrel.
It's marked 5.56 1 in 9. The lower is marked .223/5.56
I'm glad I can shoot either....I'll probably stick with .223 though.

 

[U.S. Patriot]

I have always been told that if your rifle is chambered for the 5.56, then yes you can shoot .223 with no worries. If it's chambered for .223, do not shoot 5.56. It may not damage your gun, but there is a chance. The 5.56 has a thicker casing, do to the higher pressure. By doing this they had to change the throating, to be able to use the same amount of powder. That's my understanding of the difference.

 

[sporter]

I don't worry about it.

Never had a problem shooting 5.56 in a .223 or .223 in a 5.56.

I don't think the manufacturers even know what exactly their barrels are chambered for sometimes. More like a one size fits all for .223 or 5.56

 

[tenring]

The Gun Zone -- SAAMI on 5.56 v. .223 Remington

 

[hunter_47443]

The Gun Zone -- SAAMI on 5.56 v. .223 Remington

Thanks,tenring
I'm going to read & investigate a little further when I get back home tonight.
Inquiring minds want to know!

 

[Litlratt]

I talked with Bill Wylde about this yesterday.

He said if you have a .223, try the 5.56 ammo. If you're not seeing any pressure signs, shoot it. My experience with ARs and pressure, is that you will see extraction and cycling problems prior to primer indicators.

He also said that the Wylde chamber is merely a 5.56 with more freebore. "Designed" after a 10 minute telephone conversation with someone.

 

[fireball168]

This has been hashed and rehashed on here and everywhere else.

As I'm tired of typing it again:

I threaded a lot of barrels from 2004-2006.

Some had short throats, NONE measured less than .050".

Chamber castings of these barrels typically showed either a significantly miscut chamber - the throat grossly misaligned to the bore(no rifling on one side of the throat with a significant step and full rifling on the other side), or what appeared to be a chamber cut with a reamer well past its usable life.

None of the barrels in question were even close to being a 223 Remington SAAMI chamber (.025" throat).

In a nutsehll - unless you've measured your chamber - you don't know what you've got, regardless of what is says on the barrel, how it was advertised, etc.

The barrel may be marked 5.56, maybe it was the first chamber cut with a brand new reamer - and its on the long/loose side. Maybe it was the last one before it was pulled out of service, or maybe it broke cutting your chamber and that's why it is all jacked up. The maybe(s) are endless.

Same thing is true for 223.

Since every manufacturer has a different reamer spec, and an unknown variable of how many barrels get chambered with that reamer - again, you really don't know what you've got.

The ONLY RIFLE that I've seen in the last 15 years that had a SAAMI 223 Remington chamber was a Cooper Phoenix, and it was ordered that way.

Every other 223 Remington RIFLE (SEMI OR BOLT) factory cut chamber I've come across has had at least .035", if not .050+ of throat length.

Hornady/Stoney Point OAL tools anyone?