Okay I know this is an idiot question but.

[Gunner]

Will a .223 rifle also shoot 5.56? I just want to make sure

Thanks
Landon

[patrick0685]

from what i understand 5.56 cases are slightly different from .223, but also understand 5.56 barrels can shoot both, .223 barrels you should stick with just .223, iv also heard that you can get a more accurate .223 barrel/gun than a 5.56. open to all corrections

[scratchy]

They are not the same. Weapons chambered for .223 Rem should not be used to fire 5.56 ammunition. Generally, rifles chambered for 5.56 can fire either. Do the proper homework before firing 5.56 in a .223 chambered rifle.

http://en.wikipedia.org/wiki/.223_Re...s_5.56_mm_NATO

[spencerhenry]

i read it on the internet so it must be true.

.223 and 5.56 are exactly the same in dimension according to several of my loading manuals. military brass is supposed to be thicker walled. my most accurate AR is labeled 5.56 nato, but i load it with .223

[theGinsue]

Scratchy is correct.

There are pressure considerations that can get you into trouble.

In a gun chambered for 5.56mm, you can shoot both 5.56 & .223
In a gun chambered for .223, you can ONLY shoot .223.

Everyone knows someone who says that they shoot 5.56 and .223 interchangably in any .223 rifle. While you might just get away with doing this for a while, it would be nothing short of playing roulette - it might be the first round or the 50th that blows the gun apart and takes your hands and face with it.

[68Charger]

This is the best illustration of the difference in dimensions that I have seen:

http://www.ar15barrels.com/data/223vs556.pdf

[theGinsue]

I actually had this information in a document on my work computer, so, here you are:

Source: http://en.wikipedia.org/wiki/.223_Remington

The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a 0.224-inch (5.7 mm) diameter, jacketed bullet, with weights ranging from 40 up to 90 grains (5.8 g), though the most common loadings by far are 55 grains (3.6 g).

The primary difference between .223 Remington and 5.56x45mm is that the .223 is loaded to lower pressures and velocities compared to 5.56 mm. Thus, .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.



223 Remington versus 5.56 mm NATO

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders)[2], and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56 mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56 mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56 mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[3] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

These 5.56x45mm NATO cartridges are identical in appearance to .223 Remington. They are, however, not completely interchangeable.

Using commercial .223 cartridges in a 5.56-chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223-chambered gun due to the excessive lead. [4] Using 5.56 mil-spec cartridges (such as the M855) in a .223-chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[5] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56 mm, such as many commercial AR-15 variants and the Ruger Mini-14[6], but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56 mm ammunition.

[TS12000]

There are no stupid questions, just really intricate answers

[BadShot]

And cause I'm still a little too ladled with pain killers and my search-fu is asleep..

What about the infamous .223 Wydle chambers?

[DocMedic]

One thing to be aware of is the difference between the Wylde and 5.56 NATO chamber in the freebore area before the bullet engages the rifling.

The NATO chamber is extremely forgiving. IIRC, it is .2260 - .2265 in this area, and the bullet is nominally .2240. Sort of like throwing a hotdog down a hallway. It keeps the pressures down, but doesn't guide the bullet into the rifling as well, with at least .001 per side between the bullet and the bore.

The Wylde chamber is nominally .2245 in the freebore area. That's almost nothing there. A little bit of crud on you bullet or barrel, and it's a slight interference fit. If you have ammo with long bullets like 75, 77 or 80 grain bullets, you'll notice this. Chamber a round by letting the bolt fly. Then extract it by hand. You'll feel some resistance (at least I do, with my RRA / Wilson barrel, with a Wylde chamber). That is because the bullet is sitting in that freebore area if your ammo is loaded to magazine length, and if the bore is a little bit dirty and the bullet isn't perfectly straight and centered in the cartridge case, it's dragging on the walls of the freebore area. If I haven't cleaned by barrel in awhile, it's considerably "sticky" to hand extract. Also, my RRA / Wilson / .223 Wylde barrel will blow primers on hot ammo (with 75 - 77 gr bullets), which won't in a 5.56 NATO chamber.

So, what is the "take-away? The NATO chamber is more forgiving of hot ammo and fouling. The Wylde chamber is better for target shooting but is less forgiving. There is no such thing as a free lunch. If you want "match accuracy" and shoot 5.56 NATO ammo, you get the Wylde chamber. If you don't care about "match accuracy", get the 5.56 NATO chamber.

found it on arfcom