The only difference in cases is the headstamp, and usually the price

I started a thread on this a couple years back, I called all the major players that still actually manufacture brass in the states. Rather than totally switching over machines on the line, the only difference is truly the headstamp; the specs are the same.

 

Loading some more Hornady 69gr hpbt for the AR to punch some holes in paper. I have both 5.56 and .223 brass is there any advantage of one over the other ?? Thanks...

I believe the 5.56 brass might be a little thicker and last longer because 5.56 is loaded to higher pressures than 223. For plinking I use 223 brass, when I load to 5.56 pressures I use 5.56 brass but it's not going to hurt anything by using 223 brass in 5.56 pressure loads.

 

FF,
The NATO cartridge is only loaded to higher pressure(maybe) in the US. The rest of the planet runs CIP standards, which slates them as the same, regardless of the chamber fired in.

But at least the mfgr's in the states told me they are the same, save for the stamp.

 

In general there is no significant difference between different head stamps of .223 and 5.56mm brass, or perhaps more correctly, there is more variation within individual head stamps than there is between head stamps.

There is a chart about half way down this page that will illustrate that:

223 Rem + 223 AI Cartridge Guide

You'll note that with the exception of PMP brass, all the brass sampled had average weight of each head stamp was within about 3 grains of the other head stamps - from 92.33 gr (Remington), to 96.28 gr (Federal). PMP brass is significantly heavier at 104.4 grains.

Less obvious however is the extreme spread ranging from 1.2 gr for Lapua, to 6.5 gr for Winchester. Similarly, the standard deviation of the samples vary from a low of .31 gr for Lapua to 1.36 gr for PMC.

The main take away here however is that the weight range for the Winchester brass is twice as large as the range of the average weights for all of that above head stamps (other than PMP). In other words, you could drop any of those other cases in a batch of Winchester brass and not notice any difference. It also means that with the exception of the PMP brass, you could mix all the rest of the head stamps and again not notice any significant difference unless you were really picky about your loading techniques and were seeking the absolute minimum in SD.

In any event, you'll notice that Lake City and WCC cases are as different from each other as they are from the commercial brass, and at the same time, they both fall comfortably within the range of weights for commercial brass.

Back when I was serious about shooting national match, and after I switched to an AR-15 in the mid 1990s, I started sorting brass not by head stamp or even military versus commercial brass, but instead sorted it all by weight with no regard to head stamp to obtain increased consistency.

 

As already pointed out, they are the same, except.

The 5.56 brass will have a crimped primer pocket that must be removed before inserting a new primer.

 

RE: Pressures and the differences:
THERE IS A DIFFERENCE! SAAMI and CIP Have Different Pressure Measuring Methods in their respective Specifications.
Also SAAMI Is Industry Recommendations While CIP Is Required By LAW in the EU.

Be Aware of the Differences in measurement methods and their Effects on the Actual pressure measurement results.

Best Regards,
Chev. William

 

Which is not exactly connected to the Cases, other than what I already discussed.

Mass production won't want to buy two sets of raw inputs, or change the production line(heat treat, etc), if it doesn't have to. If they can build one product and market it to multiple applications, they will. The same thing as your oil filter on your car.
This is what the manufacturers told me they do, when asked.

Likewise cartridge brass doesn't HAVE to be made by any one formula, so other than a relatively speaking mannor, assuming weight is an exact correlation to volume is incorrect.

On the side note of pressures, if anyone wants to re-hash this dead horse, here is a test that was done to this point.
5.56 vs .223 - What You Know May Be Wrong - LuckyGunner.com Labs

 

What Darkker says is true, also, just because 2 cases weigh the same, even from the same manufacturer, does NOT mean they have the SAME volume. I have sectioned Win, Rem, Fed, Norma, Hornady and PMC, none internally are the same in regard to VOLUME, weights were similar, particularly between Rem and Win brass. The volumes were vastly different. The reason was this, Rem cases have thin webs and thick walls, therefore have less volume. Win cases have thick webs that run up the sides into the walls, similar to a funnel shape towards the flash hole, and thinner walls, creating more volume. Federal cases are thick everywhere, Hornady are similar to Win but a little thicker. Norma are thin and have huge capacity compared to other brands.
I also have Lapua, but am not willing to section one due to unavailability and it's my target rifle brass, but volume is like that of Remington.
The hardness of each is wildly different, Win is harder than most, Rem is not quite as hard, Hornady is about the same and Norma is soft while Federal is softest and not that great for max pressures.
None of the commercial brass is as hard as some ADI military NATO cases I tested in 5.56 and 7.62, I also have samples of the 'cups' they use to form the brass from, some loss in weight is normal and it is hard.

Some brass work hardens far quicker than others, too, so regular annealing is necessary for long case life.

Cheers.