.223 Vs 5.56 Nato


November 26, 2007, 08:52 PM
What are the disadvatages, if any, of firing .223 in a rifle chambered for 5.56 NATO and vice versa?

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November 26, 2007, 08:56 PM
5.56 is loaded to higher pressure than commercial .223, I have never had any harm come to any of my guns by firing .223 in them.

November 26, 2007, 09:30 PM
Don't fire 5.56x45 ammo in a .223 rifle. The opposite is OK though.

November 26, 2007, 09:59 PM

November 26, 2007, 10:03 PM
Any chamber/barrel with a civilian designation (e.g., .223) that has a military semi-equivalent (e.g., 5.56x45) is going to be at much tighter tolerances than a military one. Military arms are built so that they can run fouled with a quart of wet mud and your accumulated toenail clippings for the past six months.

Yes to .223 fired out of a 5.56xx45 weapon, NO, NO, NO the other way around.

November 26, 2007, 10:05 PM
Don't fire 5.56x45 ammo in a .223 rifle. The opposite is OK though. Not unless you want to shoot it loose, or like using broken shell extractors.

More info


Gun lover
November 27, 2007, 03:35 AM
What about shooting 5.56 out of a Mini 14?

November 27, 2007, 09:45 AM
I alway thought one was the civilian version of the other. Do these cartridges also suffer minor differences in tolorances like the 308 and 7.62 NATO?

November 27, 2007, 10:06 AM
I shoot .223 commercial cartridges out of 5.56 NATO chambers all the time, no problems.
I have heard and read all the blah, blah, but haven't seen mine or anybody elses rifle fail because of .223s in 5.56 chambers,,,,yet.
I wouldn't recommend shooting 5.56 NATO out of commercial .223 Remington chambers.

I tried 5.56 NATO in my one and only Mini 14 and found the bolt would lock up and I would have to kick on the op rod handle to free the case, always remove the magazine first if you have to do this unless you have suicidal tendencies.
Stopped after 60 rounds and nine times of having to do this, no damage to the rifle though.
I have had to free up several commercial chambered bolt rifles over the years that people have fired 5.56 NATO dimenson cartridges in, no fun task.

Keith Wheeler
November 27, 2007, 02:34 PM
What about shooting 5.56 out of a Mini 14?

Here's what I find interesting about this supposed "difference".

Ruger states in all of their Mini-14 manuals something like this (from "Ruger Mini-14 Ranch Rifle"): The Ruger Mini-14 Ranch Rifles are chambered for the .223 Remington (5.56mm) cartridge. The Ranch Rifle is designed to use either standardiz (sic) U.S. military or factory loaded sporting .223 (5.56mm) cartridges manufactured in accordance with U.S. industry practice.

Colt says something similar. So does FN Herstal. So does Bushmaster...Not only do they state you can use both, they pretty much imply it's the same thing.

Also I've seen IMI military ammunition with ".223 Rem" headstamps.

_Supposedly_ .223 and 5.56mm have a different "leade", which supposedly "could" cause overpressure by loading "5.56mm" in a ".223" chamber.

I have yet, however, to find a major rifle manufacturer who says "don't use 5.56mm in our .223 rifles!!! The world will end!!!" Who does say this? SAAMI. You know, that industry organization whose members want to sell you ".223" for 30% to 50% more than you pay for "5.56mm" surplus? Follow the money. The ammo makers say it's bad, the rifle manufacturers don't.

I'm still waiting to find a major rifle manufacturer to say it's bad -- and I'm not talking somebody who just assembles AR-15s and repeats the SAAMI story, but the kind of firm that actually designs firearms and has real ballistics and mechanical engineers on staff.

November 27, 2007, 03:30 PM
I have yet, however, to find a major rifle manufacturer who says "don't use 5.56mm in our .223 rifles!!!

Good point, me neither...:scrutiny:

November 27, 2007, 03:55 PM
Page o' good poop:


The .223 Remington is the most widely-used centerfire rifle cartridge in the developed world. In its 5.56x45 military form, it is the primary issue ammunition for the U.S. Military and NATO forces. It is a popular sporting cartridge, and probably the most commonly used centerfire varmint cartridge. In our Readers' Poll, the .223 Rem (both standard and improved) ranked first among preferred varmint rounds. The .223 Rem is efficient and versatile. It can sling 40-grainers past 3650 fps, and deliver 90gr VLDs accurately at 1000 yards. Its parent case, the .222 Remington, was once a mainstay of benchrest competition. Today, with custom match bullets, the .223 Remington can still deliver impressive accuracy, shooting well under quarter-MOA in a good rifle.

.223 Remington Cartridge History

The .223 Rem was derived from the .222 Remington, a round popular with benchrest and varmint shooters in the 1950s. The U.S. Army was looking for a new, high-speed small-caliber round to replace the .308 Winchester (7.62x51). To increase velocity with a 55gr bullet, the U.S. Military bumped the .222 Rem's case capacity by pushing forward the shoulder and shortening the neck. This military modification of the .222 Remington was originally called the .222 Special but was later renamed the .223 Remington. In military metric nomenclature, the round is called the 5.56x45. For the full history of the 5.56x45 cartridge, read the 5.56x45 Timeline, by Daniel Watters.

223 Remington vs. 5.56x45--Chambering and Throat Considerations

Is the .223 Remington the same as the 5.56x45? The answer is yes and no. There ARE differences between the .223 Remington as shot in civilian rifles and the 5.56x45 in military use. While the external cartridge dimensions are essentially the same, the .223 Remington is built to SAAMI specs, rated to 50,000 CUP max pressure, and normally has a shorter throat. The 5.56x45 is built to NATO specs, rated to 60,000 CUP max pressure, and has a longer throat, optimized to shoot long bullets. That said, there are various .223 Remington match chambers, including the Wylde chamber, that feature longer throats. Military 5.56x45 brass often, but not always, has thicker internal construction, and slightly less capacity than commercial .223 Rem brass.

Should you be worried about shooting 5.56x45 milspec ammo in a .223 Remington?

The answer really depends on your chamber. 5.56 x45 ammo is intended for chambers with longer throats. If you shoot hot 5.56x45 ammo in short-throated SAAMI-spec chambers you can encounter pressure issues. The new long-throated 'Wylde' chamber allows safe use of military ammo. Wylde chambers are quite common in Rock River guns. Other manufacturers, such as Fulton Armory, offer modified "match chambers" with extended throats that allow safe use of 5.56x45 ammo in .223 Remington rifles. For a complete discussion of the .223 Rem vs. 5.56x45 question, read this Tech Notice from Winchester, and this GunZone Commentary by Dean Speir. Without belaboring the point, we'll repeat the official SAAMI position: "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."

oklahoma caveman
November 27, 2007, 04:51 PM
ok so what about the guns that are marketed as being chambered for the 223/5.56? can you shoot both in it? is accuracy changed?

November 27, 2007, 09:59 PM
Of go with a Wylde chamber and be done with it.

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