Colt AR question:

[ds92]

Hello everybody,
I'm currently considering buying a colt 6700. I'm looking for an AR chambered in 5.56 NATO. On gunbroker, or any other internet store, they all say it shoots .223 remington, but pictures of the barrel show it says 5.56 NATO. Should I go buy what the seller says or what the barrel says?

Thanks in advance,
DS

 

[cyclopsshooter]

556 and 223 are basically the same thing- 556 being the nato round and 223 commercial- there is some talk that it is problematic to use 556 in a 223 because of either case length or pressure difference but it is 100% ok to use 223 in a 556

 

[Runningman]

Go by what the barrel states. As far as I know all Colt AR-15s have the 5.56 military chamber (longer throat than the 223 Remington) even though many Colt AR variations state 223 on the lower receiver.

 

[loadedround]

Either one, your rifle won't know the difference.

 

[cbrgator]

If the barrel says 5.56, its 5.56. Good thing about that is a 5.56 chamber can shoot a .223 round.

 

[kwelz]

Either one, your rifle won't know the difference.

Wrong, Wrong, and Wrong.

You can fire .223 in a 5.56 chamber but please don't fire 5.56 in a .223 chamber that hasn't been reamed.

 

[Kangspec]

google it. lots lots info's

bottom line is what Azizza said.

 

[dscottw88]

I fire 5.56 in my saiga thats been marked .223 all the time.

 

[61chalk]

I have a Colt AR HBAR, marked 5.56, Been told 5.56 can handle higher pressure, 5.56 ammo I am told produce higher pressure than .223...so....223 would be just fine, its what I shoot. Some say not to shoot 5.56 in a .223 caliber rifle. But there will be many that say they do an no harm, some will say that .223 rifles can handle the pressure....I wouldn't worry either way with your Colt, its made for 5.56 so your .223 isn't going to harm it in any way...no worries.

 

[tdowell]

FYI, 5.56 has about 75000 psi at the breach, .223 has about 55000 psi. A weapon chambered for .223 is only designed to take rounds in the 55k range. A 5.56 round CAN cause the barrel on a .223 to explode if only build to the .223 spec. So, get the 5.56 and you're covered. If you fire 5.56 in a .223, you're risking your life. It only takes one hot round to end it, its not worth the risk.

 

[loadedround]

Azizza: The 5.56 and the 223 cartridge are one in the same cartridge for all practical shooting purposes and thousands of rounds are been fired interchangably everyday. Can you honestly say that you have actually "miked" the two cartridges have found a significant difference or are you just repeating another old wives tale? For the record I have and there is little difference. I own and shoot two AR's(Match Colt and DPMS), a Mini 14 and a Ruger 1B in 223, and all four run interchangeably w/o fuss or muss. Also for the record I have just referenced three current reloading manuals and there is nothing listed about non-interchangeability between the two cartridges. BTW the average operating pressure for both cartridges is 52,000 cup's per the Speer #14 Manual. Other shooters will definitely confirm what I have just said. Your statement is incorrect.

 

[Runningman]

Thought this was well known, but I guess not.
News and Press Releases

.223 Rem VS 5.56mm

Paul Nowak
5/4/2001
.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.


Before buying either of these two types of ammunition, always check your gun to find what caliber it is chambered for, then buy the appropriate ammunition. Most 5.56mm rounds made have full metal jacket bullets. Performance bullets - soft points, hollow points, Ballistic Silvertips, etc. - are loaded in .223 Rem cartridges. Firing a .223 Rem cartridge in a 5.56mm-chambered gun is safe and merely gives you slightly reduced velocity and accuracy. However we do not recommend, nor does SAAMI recommend, firing a 5.56mm cartridge in a gun chambered for the .223 Rem as the shorter leade can cause pressure-related problems.

Winchester Law Enforcement Ammunition

East Alton Illinois

 

[briansmithwins]

Azizza: The 5.56 and the 223 cartridge are one in the same cartridge for all practical shooting purposes and thousands of rounds are been fired interchangably everyday.... Your statement is incorrect.

Nope, he's right and you're wrong, at least according to SAAMI:

From http://www.saami.org/Unsafe_Combinations.cfm

In Firearms Chambered For...Do Not Use These Cartridges
223 Remington...................5.56mm Military

BSW

 

[kwelz]

It never ceases to amaze me how people can convince themselves of something in spite of all the evidence against their misconception. 5.56/.223 or .308/7.62 interchangeability, leaving a spring compressed will wear it out, etc.

I am sure there are a number of people out there who have fired 5.56 in a .223 chambered rifle. However there are also a lot of people out there who don't wear seatbelts, drive drunk, and/or carry handguns tucked into their pants. They are asking for trouble as well.

 

[AgentAdam]

Guns like the AR,AK74,and Mini14 may say .223 on the barrel but usually have a long enough chamber to feed anything.

 

[kwelz]

Not true Adam. At least not in the case of AR15s I have seen. Many .223 and even 5.56 from mid and lower tier manufacturers are not true 5.56 and have trouble with 5.56 ammo. I had to run a Chamber reamer on my Bushmaster to get it to function properly with Military spec ammo.

 

[krs]

Unbelievable.

What a bunch of mixed up kids! LOL!

 

[wally]

FYI, 5.56 has about 75000 psi at the breach, .223 has about 55000 psi. A weapon chambered for .223 is only designed to take rounds in the 55k range. A 5.56 round CAN cause the barrel on a .223 to explode if only build to the .223 spec

In todays legal climate do you actually think anyone with a lawyer would sell a rifle chambered in .223 not designed to be safe with 5.56 ammo?

Name names if you know. Actual examples of 5.56 exploding in .223 barrels would be even better (reloads don't count!).

I'd only worry about it, if the .223 gun in question was made before the M16 was introduced, are there any?

Nope, he's right and you're wrong, at least according to SAAMI:

From http://www.saami.org/Unsafe_Combinations.cfm

But this makes the real question become who is selling rifles actually chambered in .223? I'd love to see the warnings and disclaimers in their owner's manual. They all say don't use reloads, but that doesn't stop anybody now, does it? I'm sure far more guns have been blown up using reloads than from shooting 5.56 in .223 guns.


The SAAMI site also says:

In Firearms Chambered For: 9mm Luger (Parabellum)

Do Not Use These Cartridges: 9mm NATO (Military) followed by some that won't fit the chamber and some that will like .380ACP, but are obviously wrong.

--wally.