5.56x45 SAAMI cartridge and chamber drawing

[Koda]

I can find the cartridge and chamber prints from SAAMI but I cant find the same for 556.

Can anyone share where I can get the cartridge and chamber drawings for 5.56?



Reference 223:

Read More

 

[Local Loader]

Not quite too that extent but the Hornady reload books have info.

 

[Koda]

Not quite too that extent but the Hornady reload books have info.

I dont have that one.

Arent the chambers supposed to be the same except the throat?

 

[Local Loader]

This is the info they give

 

[bcp]

Cartridge case, if that helps:



Bruce

 

[Koda]

This is the info they give
View attachment 1372292

super helpful.
Though it doesnt give the one dimension I need, the rest are the same I can conclude the one is the same.

Short version is I think my 556 chamber is cut at min or possibly too small. Using 223 shoulder dims I can get sticky case extraction in my 556. I need to bump the case shoulder even smaller to my 556 chamber.

 

[rhollister71]

The 5.56mm NATO chamber, known as a NATO or mil-spec chamber, has 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 Remington chamber, known as 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 (Rock River Arms)[70]​ or the ArmaLite chamber, which are designed to handle both 5.56×45mm NATO and .223 Remington equally well. The leade of the .223 Remington minimum C.I.P. chamber also differs from the 5.56mm NATO chamber specification. The casings and chambers .223 Remington and 5.56×45mm NATO are virtually the same dimensions, but due to the fact that .223 Remington is designed to handle much lower pressures than the 5.56×45mm NATO the rounds are not completely interchangeable. Firing a 5.56×45mm NATO round out of a rifle chambered in .223 Remington could be injurious or fatal to the user as well as the gun, however .223 Remington ammunition can be fired safely from almost any rifle chambered in 5.56×45mm NATO as the NATO specified rifles can handle much higher chamber pressures than the .223 Remington is capable of producing.

 

[Koda]

Cartridge case, if that helps:

View attachment 1372294

Bruce

perfect, thank you .

its interesting they use a different shoulder datum (.3017 dia, basic)

 

[Koda]

The 5.56mm NATO chamber, known as a NATO or mil-spec chamber, has 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 Remington chamber, known as 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 (Rock River Arms)[70]​ or the ArmaLite chamber, which are designed to handle both 5.56×45mm NATO and .223 Remington equally well. The leade of the .223 Remington minimum C.I.P. chamber also differs from the 5.56mm NATO chamber specification. The casings and chambers .223 Remington and 5.56×45mm NATO are virtually the same dimensions, but due to the fact that .223 Remington is designed to handle much lower pressures than the 5.56×45mm NATO the rounds are not completely interchangeable. Firing a 5.56×45mm NATO round out of a rifle chambered in .223 Remington could be injurious or fatal to the user as well as the gun, however .223 Remington ammunition can be fired safely from almost any rifle chambered in 5.56×45mm NATO as the NATO specified rifles can handle much higher chamber pressures than the .223 Remington is capable of producing.

yes, this Im aware of.
Im dealing with sizing 223 cases to fit my 556 chamber. And to make things worse Ive discovered my 556 chamber headspace might be cut on the small end.

 

[osprey]

The 5.56x45 is a nato spec cartridge and the .223 rem is a saami spec cartridge. That is why there are no saami spec drawings for the 5.56. For all intents and purposes the external cartridge dimensions are identical. As noted above the only dimensional difference in the chambers is the longer leade in the 5.56. The 223 wylde chamber leade length is in between 223 and 5.56. At least that is my interpretation of them.
It is possible you have an out of spec chamber in your 5.56 gun but more likely it is cut on the short side of the spec range for headspace. Couple this with your 223 wylde possibly cut on the generous side of spec for headspace and you will have the formula for what you describe. I have the exact situation when loading for a 223 wylde gas gun and a 5.56 nato bolt gun. Ammo loaded to fit the boltie works in both but ammo produced for the 223 wylde, bumping the shoulder back .002" from fire formed, is very hard to chamber in the boltie. The battle is real.

 

[Koda]

...in your 5.56 gun but more likely it is cut on the short side of the spec range for headspace. Couple this with your 223 wylde possibly cut on the generous side of spec for headspace and you will have the formula for what you describe.

I suspect this is what I have going on, my guess is my 556 chamber is near the very bottom of the spec which is why I wanted to see the nato drawing. Theres still a chance my 556 chamber is too small because Ive had rare but a few 223 factory ammo sticky in the chamber. I do know if I bump my shoulder to just fit the Wylde chamber it wont fit the 556 chamber. The drawing BCP shared is helpful but doesnt show the same datum point so I still cant measure it but Im going to move on and just use the 223 spec. I want to develop 1 round for both rifles so I need to bump the shoulder to fit the (my) 556 and use the Wylde chamber to develop the load since its rated for a lower chamber pressure.

 

[osprey]

My situation is pretty similar and depending on the bullet and powder combo, I can either keep the load with the same powder weight with the shorter headspace or I have to drop a couple tenths of a grain to keep from showing pressure signs when brass is sized to fit both chambers.

 

[Koda]

Id like to keep the load the same for both rifles, but if this becomes any more complicated then I will just make a load for each rifle and call it good.
We will see what happens, I mostly load for the AR just to learn more... otherwise not a high priority but its fun.

 

[Local Loader]

I'd just do the one for the 5.56 and call it good. Does any of the factory 5.56nato ammo match what you're looking for when you measure it?

 

[Koda]

I'd just do the one for the 5.56 and call it good. Does any of the factory 5.56nato ammo match what you're looking for when you measure it?

I dont buy 556 ammo anymore since I got the 223Wylde.
I have ran plenty of 556 in the past and no issues. Ive never measured any 556 cases and dont plan to handload 556 cases.
I just want a pet load for the 223 and think it would be cool if it also ran accurately in the 556 is all.

 

[Local Loader]

Well, might be worth it to get some to use as comparison to help develop the load.

 

[Koda]

Well, might be worth it to get some to use as comparison to help develop the load.

Im not certain how shooting 556 will help me develope a 223 handload?

 

[Local Loader]

If you're trying to match a 556 chambering it's a start point to work with.

 

[titsonritz]

Nor will you because 5.56x45 is not a SAAMI-spec cartridge, it is NATO spec.

https://www.thetruthaboutguns.com/5-56-vs-223/

 

[Pepe-lepew]

Headspace does not make sticky extraction.

In your other post with the split brass I responded you have bent rims from being over gassed. Severely over gassed rifles will have extraction problems. Besides the extractor bending the rim, it will tear off the rim if it is bad enough.

If you want a lesson on loading for a service rifle, stop by my High Power/Garand rifle match clinic Friday at 6pm at Albany. I can cover reloading for AR's in depth at the end of the class if you want.