5.56 brass vs 223

[cbr600f3]

This is a bit confusing to me. I have both 223 and 5.56 brass. I have 223 reloading dies, first will these work with the 5.56 brass, second do i need to reduce loads by 10% when using the 5.56 brass?
Is there a way to tell the difference in the two brasses with either measurement or weight differences?

 

[ArchAngelCD]

There are no such thing as 5.56mm dies, you .223 dies will size 5.56mm brass just fine.

There are some brands of 5.56 brass that do have a slightly smaller capacity than commercial .223 brass. You can check by filling each with water or even a ball powder to see if your 5.56 brass requires less powder to achieve the same velocity as commercial brass.

 

[Fishinfool]

Commercial .223 and military 5.56 brass has the same outside dimensions, and .223 dies will work with either. Military brass is sometimes a little thicker, hence heavier, than commercial .223 brass. Weigh a half dozen .223 brass of the same headstamp, and a half dozen of the same headstamp 5.56 brass, and that will answer your question about weight / capacity.

If the military brass does prove notably heavier, use starting loads, and work up, as you would with any load. There is not usually enough difference to worry about unless loading hot. An individual rifles chamber specs / free bore / bore diameter can make just as much or more of a difference in pressures.

Larry

 

[Bruce51]

This debate has been raging on for as long as the two designations have been around.

Good answers already to the lack of almost any difference between the designated rounds.

One is a metric size, one is American but the cartridge overall is the same.

I have weighed both 5.56 and .223 cases with no actual difference noted.

Now I have fired 5.56 rounds and they are definitely faster than hand loaded .223 even if loaded in 5.56 cases.

So I will conclude the 5.56 ammo is hotter than anything that I would load in either a 5.56 or .223 marked case.

I even fired some 5.56 rounds in a .223 chambered gun and nothing bad happened. Really, nothing at all!

So use due diligence and work up a good load, for your gun, using either type of case.

BLM

 

[SMSgt]

My Rem 788 .223 has never fired a commercial round. Every round through it has been as reload in a 5.56 case, reloaded to typical .223 data.

The difference between a .223 and 5.56 barrel is the length of the throat, not the casing.

 

[2ndAmendmentNut]

As others have pointed out 5.56 and 223 are the same dimensionally on the outside. It is generally believed that 5.56 or military marked cases are thicker therefor have less internal capacity. I have found that thicker cases are not always a given. The big difference between the two is the fact that most military brass has a crimped in primer where as commercial brass typically does not. I remove crimped in primers with a universal de-priming die and then swage the primer pocket with an RCBS primer pocket swager. I would recommend shorting any brass for caliber by head stamp and working up loads from suggested starting data.

 

[moxie]

There MIGHT be a small difference between cases, but you find similar differences between brands of .223, even within the same brand.

I use them interchangeably. I note no differences, other than 5.56 USUALLY have crimped primers, while .223 USUALLY do not.

As noted above, use .223 dies for all cases, .223 and 5.56.

 

[tlay]

What others have said is true. I have reloaded a lot of military brass. The difference I have run into is the length. I guess it depends what they were fired in. I have found a length difference of .025. Check the length and trim the longer ones.

 

[BlueOvalBandit]

A lot of myths and misconceptions in the differences of military 5.56 cases and .223 cases. Weights do not necessarily correlate with case capacity. Unless you are a benchrest shooter and the utmost consistency matters, its a moot point. Prep, then load the same, small changes of internal volume are negligible for most intents and purposes.

223 Rem + 223 AI Cartridge Guide within AccurateShooter.com

The biggest issue is crimped primer pockets and oal as some military chambers are very generous ie the saw

 

[358156hp]

Some military case lots actually have more capacity than some civilian cases too. Start with the beginning loads listed for .223, do not use 5.56 data! and work your way up or down as needed. Don't ever use 5.56 data unless you know without a doubt how your barrel is chambered. Also, 223s are really fussy about case length, make certain you keep your cases below maximum length. Almost every AR I've encountered locally has had the civilian 223 chamber & throat.

 

[gregintenn]

Same brass.

I load LC556 brass, as well as PMC, FC, Winchester, Remington, etc., with a 55 grain Hornady, and a max load of IMR 4320, and shoot them interchangeably.

This results in 1" 100 yard groups from my Bushmaster carbine, and 2" groups from my Ruger Mini 14 Ranch Rifle. This is better than any factory load I've found, and is economical as well.

Trim your brass to a common length, full length resize, and be sure to remove the crimp from the military brass, or else you'll find some of the primers will give you a fit when you attempt to seat them. A good twist with your case mouth deburring tool in the primer pocket will get this job done.

 

[bigedp51]

cbr600f3

I have two AR15 rifles and a bolt action Savage .223 that are less than four years old, the throat on my Savage .223 is longer than my AR15 rifles. The only difference that matters is the throat length of "some" .223 rifles are shorter and if military M885 is fired in these rifles the chamber pressure will be higher. The SAAMI interchangeability warning for the .223/5.56 did not come out until 1979 with the adoption of M885 military ammunition.

Below is a very good link that will answer many of your questions.

5.56 vs .223 – What You Know May Be Wrong

http://www.luckygunner.com/labs/5-56-vs-223/

Below are the weight and internal capacity of .223/5.56 cases from the link above provided by BlueOvalBandit.

Military Lake City and commercial contract cartridge cases must meet higher milspec requirements. The brass is harder in the base to better withstand larger diameter and longer headspaced military chambers. For reloading the AR15 it is the best brass you could use for reloading.

I have three five gallon buckets of once fired brass made up of Remington, Federal and Lake City brass.

I separate my brass by headstamp for reloading purposes "BUT" the weight and internal capacity of these cases is very close. I reload the majority of my AR15 ammunition and cases with 24.7 grains of H335 and 55 grain bullets for 100 yards or less practice ammunition. This is a mild load and easy on the brass to extend the reloading life of the cases.

My only warning to you is Federal brass is noted for being soft and I had a 50% failure rate with Federal cases marked LC 05 for loose primer pockets after the first firing. I just found and ordered a gauge for checking for oversized primer pockets. This solves the problem of seating primers only to find out the primer pocket is too loose and removing the primer from a bad case.

The cartridge cases below used in Federal ammunition do NOT meet NATO standards and do NOT have the NATO symbol on the case. Federal has had a ongoing problem with some lots of soft brass in ammunition and if you reload they can cause problems.

Also if you have a AR15 you should only use primers with a cup thickness of .025 to prevent slamfires.

 

[W.E.G.]

Don't assume that differences in case-weight have anything to do with internal capacity.

The differences in weight can just as easily (and more probably) be accounted for by the depth of the cut of the extractor groove.

 

[tlay]

I too had a problem of loose primers on some military brass. I had some blow out and lodged in the trigger. I solved this by using my wife's fingernail polish. There are products you can use to seal the primers for better moisture protection that do the same job. After you finish the reloading brush a small amount around the primer. This will help keep the primer from blowing out on a loose pocket. There is no difficulty in removing these spent primers.

 

[gregintenn]

I too had a problem of loose primers on some military brass. I had some blow out and lodged in the trigger. I solved this by using my wife's fingernail polish. There are products you can use to seal the primers for better moisture protection that do the same job. After you finish the reloading brush a small amount around the primer. This will help keep the primer from blowing out on a loose pocket. There is no difficulty in removing these spent primers.

I've noticed some Federal commercial brass with loose primer pockets, but so far not military stuff. I've yet to have one back out so far, but I could see it happening at some point.

 

[tlay]

A lot of my 223 reloads I am saving for "just in case". I want these rounds to be as reliable as possible. This is just one more step to make them so.

 

[mtgianni]

I too had a problem of loose primers on some military brass. I had some blow out and lodged in the trigger. I solved this by using my wife's fingernail polish. There are products you can use to seal the primers for better moisture protection that do the same job. After you finish the reloading brush a small amount around the primer. This will help keep the primer from blowing out on a loose pocket. There is no difficulty in removing these spent primers.

I have successfully used fingernail polish to seal cases from moisture infiltration. I do not consider it as an aide to pressure protection. If you are loosing primers when firing the brass should be crushed and tossed. My eyes are worth more than the cost of brass.

 

[DWalt]

All of the above is correct. But one other factor distinguishes .223 from 5.56mm ammunition - peak chamber pressure. SAAMI pressure specs govern .223, while NATO pressure specs govern 5.56mm. These are two completely different measurement methods and are not related. However, I have read that if 5.56mm military ammunition is pressure tested using the SAAMI method, the peak chamber pressure of 5.56mm somewhat exceeds .223, i.e., the 5.56mm NATO rounds are loaded somewhat "hotter" than civilian .223, but both are within their respective pressure specifications.

 

[Road Rat]

 

[bigedp51]

All of the above is correct. But one other factor distinguishes .223 from 5.56mm ammunition - peak chamber pressure. SAAMI pressure specs govern .223, while NATO pressure specs govern 5.56mm. These are two completely different measurement methods and are not related. However, I have read that if 5.56mm military ammunition is pressure tested using the SAAMI method, the peak chamber pressure of 5.56mm somewhat exceeds .223, i.e., the 5.56mm NATO rounds are loaded somewhat "hotter" than civilian .223, but both are within their respective pressure specifications.

The only difference between the American SAAMI .223 and Military 5.56 is the length of the throat. All that NATO standards means is Europe get to keep using their CIP standards of measuring chamber pressure at the mouth of the case. Our American SAAMI measures chamber pressure at the mid point of the cartridge case. American SAAMI .223/5.56 read as 55,000 psi and European CIP (NATO) pressures would read as 62,000 psi at the case mouth.

Below are the military milspec pressure requirements for the 5.56 that are used by commercial ammunition manufactures making 5.56 ammunition for our military. Please note that our military even when using the copper crusher method uses the term PSI. This sometimes causes confusion when people look at TM 43-0001-27. The pressure standards below are the same as for the American SAAMI .223.

MIL-C-9963F
15 October 1976

MILITARY SPECIFICATION
CARTRIDGE, 5.56MM, BALL, M193

3.7 Chamber pressure.

3.7.1 Measurement by copper-crush cylinder.-The average chamber pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not exceed 52,000 pounds per square inch (PSI). The average chamber pressure plus three standard deviations of chamber pressure shall not exceed 58,000 PSI.

3.7.2 Measurement by piezoelectric transducer.-The average chamber
pressure of the sample cartridges, conditioned at 70° ± 2°F, shall not
exceed 55,000 PSI. The average chamber pressure plus three standard
deviations of chamber pressure shall not exceed 61,000 PSI.

Traditionally military chambers are larger in diameter and have longer headspace settings. Look at item C below, the military chamber is .002 larger in diameter. The military throat is larger in diameter and longer than SAAMI "recommendations" see items G and N

The throat on my Savage .223 with a 1 in 9 twist is .0566 and "LONGER" than military requirments. .223 rifles with a 1 in 12 or 1 in 14 twist normally have the shorter "SAAMI" throat and if 5.56 M855 ammunition is fired in them the pressures will be 5,000 psi higher than normal "rated" .223 ammunition.

Again the SAAMI interchangeability warning for the .223 and 5.56 did not come out until 1979 with the adoption of military M885 ammunition and the change in military throat length.