Warning: Newb Question

 

 

Is a .223 shell and a 5.56 shell essentially the same thing? As in can they be fired out of the same weapon?

 

for example , alot of ar style rifles are listed : .223 Reminton/5.56 NATO under caliber, though Im confused when people say it HAS to be either or.

 

Thanks

i believe you can shoot 223 out of a 556 chamber but dont do it reverse and the 223 in some way is slightly smaller i believe in the necking. unless it has a wylde chamber than you can shoot either or

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There always seems to be a lot of confusion over the difference between a .223 and a 5.56 chamber. Is it safe to shoot this? Is it safe to do that? More confusion is added when some manufacturers advertise rifles with .223/5.56 chambers. I found this 'excellent' explaination on Wikipedia (http://en.wikipedia.org/wiki/.223_Remington) and wanted to share it on this forum.

 

The .223 Remington is a sporting cartridge with the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a .224" diameter, jacketed bullet, with weights ranging from 40 up to 90 grains, though the most common loadings by far are 55 grains.

 

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .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.

 

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), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56mm 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 5.56mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56mm 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[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

 

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 leade. [3] 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.[4] 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, 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.

If the barrel is marked both then both are OK. If the barrel is marked 5.56 then both are ok. If the barrel/owners manual states specifically 223 the 5.56 is NOT ok.

the actual shell is about the same or is the same but the bullet of the 223 is actually smaller then the 556

the actual shell is about the same or is the same but the bullet of the 223 is actually smaller then the 556

 

 

Uhhhh, no.

 

Both use 5.56 mm bullets, which translates to .223 or .224. Both can use various bullet weights from 35 grs up to 90 grs. depending on twist rate and leade. So whether you meant smaller dimensionally, or smaller in regard to weight, you're wrong on both counts. The differences are as enumerated in the Wiki quote in one of the previous posts.

 

Adios,

 

Pizza Bob

I think of it as analogy that you can shoot 38 special out of a 357 but you can't shoot 357 out of a 38. Because the 38 special gun isn't built to handle the 357 pressures. With the 38 special they dummy-proofed the gun/cartridge. With the 223 rifles, you can't be a dummy.

You can shoot .223 in a .556. The reason is CUP which is higher in .556. The reverse is true for .308/7.62X51.

There are two key differences for 5.56 and .223. First the brass. 5.56 has a thicker web and smaller case volume, or at leas it can. This is to deal withthe higher pressures soecced for 5.56. The 5.56 chamber is cut with a longer leade. This means the bullet mives farther before contacting the rifling. This gives the burning powder charge more space toexpand before pressure spikes.

 

Theoretically, match .223 is tightest and 5.56 is te loosest, and .223 wylde, 5.56 sam-r, and a bunch if others in between. In reality, if you look at chamber cutter dimensions, the tightest one sold as 5.56 is tighter than the loosest one sold as .223. So there are no guarantees, just playing it safer.