Loads for 556?


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Bowfishrp
March 26, 2008, 05:05 PM
Ok I think this sounds stupid but do I need to hunt down different loads for 556 brass or can I use the same loads for 223? These will be shot in ARs chambered for 556 but would prefer to use the same loads as 223 just dont know if that would be safe.

Right now my prefered 223 load is 22g of h322.

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K3
March 26, 2008, 05:07 PM
Right now my prefered 223 load is 22g of h322.

Bullet weight?

rcmodel
March 26, 2008, 06:14 PM
5.56mm NATO is the same thing as .223 Remington in most reloading manuals.

Military brass may have slightly less internal capacity, but if you start with .223 starting loads, and work up as you should do anyway, it is all the same.

rcmodel

strat81
March 26, 2008, 06:27 PM
Military brass may have slightly less internal capacity, but if you start with .223 starting loads, and work up as you should do anyway, it is all the same.
+1. That's how it should be done with any brass, or any change in components, but especially with mil brass.

You can use .223 data in a 5.56 chamber. Beware, some manuals have bolt-action and semi-auto sections. Stick with semi-auto for your AR.

rcmodel
March 26, 2008, 06:32 PM
Stick with semi-auto for your AR.Maybe, maybe not!

Hornady for one, only lists AR-15 5.56MM NATO loads with the 68 & 75 grain match bullets.

If you want 55 grain BT-FMJ w/c, or any of the varmint / hunting loads, you are going to be using .223 Rem. data.

rcmodel

strat81
March 26, 2008, 06:35 PM
Good point, rcmodel. I was thinking of the Sierra manual, specifically.

Bowfishrp
March 26, 2008, 06:38 PM
Sorry forgot to mention that the h322 load is 22g with a Hornady 55g FMJBT. My Weatherby 223 loves this load but I wont be shooting 556 in it just in ARs.

If I load them the same as 223 is there any reason to think they wont shoot the same?

rcmodel
March 26, 2008, 06:44 PM
Again, for reloading purposes, they are the same.

The only differance is GI 5.56 may be loaded to slightly higher pressure then Commercial .223 Remington.

Reloads are not GI issue 5.56 NATO, even though you may be using GI cases.

rcmodel

Bowfishrp
March 26, 2008, 09:34 PM
That's exactly what I needed to know, thanks!

Sunray
March 26, 2008, 09:39 PM
"...wont be shooting 556 in it just in ARs..." You'll have to work up a load for each rifle and full length resize every time. Use .223 data.
The AR will require FL sizing every time. You can neck size only for a bolt action should you choose to do so. Using a different brand of brass for your AR and bolt action is an easy way of keeping neck sized brass separate from the brass for the AR.

Ridgerunner665
March 26, 2008, 09:56 PM
I'm not going to say much about this because I have had my wrist slapped once already....but rcmodel said "slightly higher pressure"...The two rounds are different...

One big difference is pressure. It becomes a bit confusing, as the pressure for the two is not measured in the same way. The .223 Rem. is measured with either Copper Units of Pressure (c.u.p.) or -- more recently -- with a mid-case transducer in pounds-per-square-inch (p.s.i.). The military 5.56x45 mm cartridge is measured with a case mouth transducer. The different measuring methods prevent a direct comparison, as a case mouth transducer gives lower numbers on identical ammunition when compared to those from a midcase transducer. That's because the pressure is measured later in the event, after the pressure has already peaked. According to Jeff Hoffman, the owner of Black Hills Ammunition, military ammunition can be expected to hit 60,000 p.s.i., if measured on a Sporting Arms and Ammunition Manufacturers' Institute (SAAMI) mid-case system. Black Hills loads maximum average pressure is 55,000 p.s.i., while a 5.56x45 mm measured with a case mouth transducer has a maximum average pressure of 58,700 p.s.i....

And that info is straight from Black Hills Ammunition...and I have more of it.

taliv
March 26, 2008, 11:58 PM
like ridgerunner said, the fact that the different methods prevent a direct comparison means that it's not safe or advisable to take a published 223rem load and attempt to extrapolate a 556 load.

for example, this sort of logic will get you in big trouble: "60k is 20% more than 50k PSI so because my AR has a 556 chamber, I can add 20% more powder or keep adding powder until I get to 20% more velocity than the listed 223 max"

that doesn't change the fact that published data is usually conservative and lots of people safely go beyond "max".

the important part is that the way you do it hasn't changed just because you have different numbers (223vs556) on the side of your barrel. start low and work up.

JFettig
March 27, 2008, 11:55 AM
keep in mind that your AR likely has a 5.56 chamber and not a .223 chamber. The throat and free bore length may be different. I know my free bore length is quite a bit longer than a .223 chamber.

Jon

taliv
March 27, 2008, 12:13 PM
your AR likely has a 5.56 chamber and not a .223 chamber.

what makes you say that, jfettig?

Ridgerunner665
March 27, 2008, 01:25 PM
Heres another tidbit of info for ya...

5.56 mm NATO versus .223 Remington

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 5.56 mm NATO measure chamber pressure at a the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000 psi (140 MPa) difference in pressure measurements. That means that advertised pressure of 58,000 psi (400 MPa) for 5.56 mm NATO, is around 78,000 psi (540 MPa) 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 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) or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

rcmodel
March 27, 2008, 02:40 PM
Military cases are made from thicker brass than commercial cases,This is always true with .308 & 30-06 GI brass.

Not so much with 5.56.

I happen to have a 50 cal ammo can full of old LC brass that is slightly lighter then commercial .223 Remington brass I bought new last year.

The only way to be sure what you have is to weigh several sized & trimmed GI cases and compare them against the commercial .223 brass you have been using.

If they weight the same or less, they don't have thicker walls and less capacity just because they are GI cases!

rcmodel

JFettig
March 28, 2008, 09:12 PM
The throat dimensions on a 5.56 aren't the same as .223, one round that is fine in 5.56 may not be ok for .223, If I had loaded up some of those soft points the same length I used in my AR and put them in the rem700, they would have hit the rifling and could potentially result in a disaster because they would be jammed into the rifling.

Many ARs have 5.56 chambers, but not all, just different throat and freebore geometry.

Jon

Bullet
March 30, 2008, 12:47 PM
Bowfishrp

You might look here - Lots of info -

http://www.6mmbr.com/223Rem.html


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