Loading 223 and 5.56 together?

[Ruger 15151]

Hi guys

I have been reloading pistol only for about 3 years. I have been waiting until I shoot through my 223/556 factory ammo stash until it was depleted before I started loading for my AR15.

Lately, I have starting processing the brass I have been collecting for my AR and noticed I have a pretty good mix of 223 and 556. 223/556 head stamps aren't the easiest or quickest to read. Originally, I thought I could separate the two easily by looking for a crimp. However, I have a bunch of 223 cases that are also crimped.

I want to load rounds for plinking and not worried about 500 yard accuracy. However, do I need to sort the 223 from the 556 brass and load separately or can I just use 223 load data for both. I would be loading well below 223 max pressure. Is 200 - 300 yard accuracy effected much by the difference in case volume?

Whats best practice?

 

[GT1]

The only difference is the number on the head stamp. Brass is the same.

 

[Blue68f100]

You will have a mixed case volume too. The 5.56 brass normally is heavier and has crimped primers, as well as some commercial 223R. At the lower loads it will not make much difference on plinking but it will impact accuracy. For the best accuracy try to keep the mfg separate.

 

[GT1]

Nope, 5.56 will not normally be heavier. The brass is the same. The difference is in the chamber

 

[Blue68f100]

Some of the one I have weighted run 5gr heaver than 223R. All depends on the mfg. A neighbor of mine ran into this and blew some primers.

 

[Walkalong]

.223/5.56 brass weights overlap. 5.56 is not always heavier.

Weigh them and see, log what weights you are using.

When I am loading .223/5.56 brass if I have one that comes along and the powder sits much higher in the case/neck than all the others I simply pull it out and scrap it.

 

[denton]

Lake City 5.56 and Federal brass have higher case capacity than any other cases I have tested. That will make a difference. Putting a 5.56 load designed for LC brass into a case with less capacity will result in higher pressures. How much higher? Heckifino.

Personally, I shoot only one brand of 5.56 brass in order to avoid this problem. Fortunately, this brand of brass is copiously available for free, since our local LEOs leave piles of it at the range.

Military 308 and 30-06 brass is thicker than commercial brass, and hence has less case capacity.

 

[Bushpilot]

Some 5.56 brass is thicker with a lower case volume then 223 and some isn't....

 

[MEHavey]

Weigh them and separate into heavy/light groups
Ignore manufacturer beyond that for mid-pressure plinkers

 

[Varminterror]

Run middle of the road load, then the weight/volume difference won’t make anybody cry.

 

[lightman]

Best practice would be to separate by headstamp. For plinking ammo in an AR you should be ok mixing them if you stay under the max loads. Those commercial cases with crimped primers are a pain!

 

[Hondo 60]

You can shoot 5.56 through your .223 chambered AR-15—but you may regret it.
Since 5.56mm Mil-Spec ammo is loaded hotter,
it has higher chamber pressure. Built to SAAMI specs, not Mil-Spec,
the .223 chamber is ever so slightly smaller than a 5.56 Mil-Spec chamber.

I try like heck to keep them separate by keeping the fired brass in the box it came in.

Maybe it's my OCD.
Just my 2¢ worth.
YMMV

 

[GT1]

If we were talking 1968 brass, maybe(I doubt it). That thicker case wall thing is internet myth in this caliber
Lake City petitioned SAAMI(?) years ago to standardize the brass, it was granted. 5.56 and .223 brass is identical and has been for a long time.

 

[Toprudder]

Myth buster: I recently purchased some commercial Starline 223 brass. They weigh ~ 8gns more than the typical LC and PMC brass that I have (100gn vs ~92.5). And before someone chimes in that the weight of the brass doesn't mean the case volume is different, the reason I weighed the cases was because the powder was higher in the neck before I seated the bullet.

Having said that, I would say that if you stay in the mid-range of most 223 data, you will be fine for just plinking ammo. The AR 5.56 rifles can take ammo loaded hotter than commercial 223 ammo.

 

[Walkalong]

Having said that, I would say that if you stay in the mid-range of most 223 data, you will be fine for just plinking ammo

Yep, my plinkers are below max. But I still look at each powder charge in the case before I seat a bullet and if one has the powder visibly higher than the rest I pull it out and scrap it.

 

[jmr40]

Military brass is usually thicker and has less volume, and more speed/pressure with the same powder charge. But there is just as much difference between different brands of commercial brass. It doesn't matter whether or not it is stamped 223 or 5.56 it is best to separate the brass by manufacturer before loading.

FWIW I don't load for 223/5.56, but I do for 308/7.62 and the same principles apply. As long as you are working with mid level loads it isn't dangerous to use mixed brass, but accuracy won't be optimum. Even with the same powder charges some brands of brass may be 50-100 fps faster than with another brand of brass. When working close to max a load that is fine in one type of brass may be an overload in another. Once again the 223/5.56 stamp isn't the important part.

You should start low and work up. I've found that there isn't enough difference between Remington, Hornady, Winchester, or Nosler brass to worry about. I get equal speeds and results in all of them with the same loads. I've found that with Federal or LC brass I need to use 1 to 1.5 gr less powder to get the same speeds. But I still don't mix brass with the same loads.

Here is what I do. I may load all 150 gr bullets in Remington brass. I may load 165 gr Hornady bullets in Winchester brass and 165 gr Noslers in Hornady brass, and reserve 150 gr plinking loads for the Federal brass. The 180 gr loads are in Nosler brass.

 

[Ireload2]

Anytime you have mixed head stamps you may have variations in weight and volume.

I like to check case weights to know if the variations are significant and to throw out any outliers.
The specific gravity of brass is about 8X the specific gravity of powder. So it takes about 8 grains of brass to take up the volume of one grain of powder. That just means that plus or minus a grain does not mean much volume change when the density of brass is considered.

 

[rsrocket1]

For me, I've found that for 100 yard plinking, any case will do and 55g fmjbt work fine. For more gratification, sorting by headstamp will get you in a 2" circle pretty easily with range fodder bullets.



But sometimes, even your best efforts aren't as good as cheap $6/box ammo if that's what your gun likes. This is PMC Bronze out of a 20" AR.



This would still be barely acceptable at 300 yards unless you're ringing a 3"-18" gong but it will explode a can of soda nicely at 100 yards.

Inside 100 yards just about anything will be fine so that's how I load my mixed brass range pickups.

 

[Load Master]

I think there is more miss information about 223/556 cases than any other cartridge.