.223 brass

[Osuvet85]

New to reloading, I know there is a pressure difference between .223 and 5.56, but is the brass dimensionally the same? My mini 14 and my AR can use either, but I have a bolt action .223 that should only use that load. If I load 5.56 brass as a .223, is it a problem? Thanks in advance.

[steve4102]

The pressure difference is in the loaded factory rounds. Once the round has been fired the brass is identical, cept the 5.56 will have a Crimped primer pocket. After you decap the primer, remove the crimp.

[MaxACL]

I've heard that the 5.56 has a thicker wall which means lessor interior volume which means... well, I don't know.

[Metal god]

Dimensionally the cases are the same so once they've been fired you can load either for either just work up the loads from min charge and you should be GTG .

In fact if you look at your manual you will see that some 223 loads when using the same powder and bullet allows a higher powder charge then the 5.56 load does . That sounds like the 223 is allowed higher preasures when reloading . I've yet to find anyone to explain why there is close to no 5.56 data that has more powder or velocity then the 223 data when using the same components .

I've only used IMR 4895 & 4064 when loading for my ARs and I can't get anywhere close to the 3262fps I get from XM193 loads . The most velocity I've gotten is 2850fps using 25.5gr and that fills the case pretty good . I could likely force another grain in there , It would be quite compressed but feel no need to .

NATO clearly loads there rounds hot and that may be a big reason they require the primers to be crimped . I'm thinking if I could get 3200+fps from a 16" barrel I'd be blowing primers . At least with the powders I'm using now .

Keep all your brass in the same lots separate ( head stamps and years ) and work up your loads from your manuals min charge and you should not have an issue . At minimum I feel you should use the the same brand of brass in the same lots but if you want to mix years . Just weigh the different year cases and compare . I've been told for 308 Win , for every 10gr difference in case weight you need to adjust your powder charge by .5 to 1gr . Now the 223 case in much smaller then the 308 so I'd think you would half the difference . Maybe for every 5gr difference in case weight you adjust your powder charge . This should resolve any case wall thickness issues just be sure to always work your loads up from min .

[Marco Califo]

I've heard that the 5.56 has a thicker wall which means lessor interior volume which means... well, I don't know.

Let me guess: You heard that from Bubba, whose friend Tony overheard someone at the gunshow talking about what someone named Stinky, heard at the barbershop in the next town down the highway, while he was flipping through the Shotgun News, swear on a stack of pancakes it was also true that all military primers are yellow colored ever since President Grant defeated the Italians in Tripoli.
People keep repeating this old wive's tale.
It is FALSE for 223/5.56
Read this fine article about the cartridge and see the table of actual case volume measurements.
http://www.accurateshooter.com/cartridge-guides/223rem/
There is no significant difference and Lake City USGI cases and commercial brass. In fact, LC 5.56 have slightly higher volume than some commercial brass, including some old Lapua cases.

Where that "story" is true is in regard to the 308 / 7.62 cartridge where case volumes are all over the place and it is wise to reduce starting loads further when using Lake City brass. But don't feel too bad. Barnes still repeats that old myth on their 5.56 copper load data here:
http://www.barnesbullets.com/wp-cont.../5.56-Nato.pdf
It is still false.

The main difference in 5.56 versus 223 has more to do with the rifles chamber being longer in the 5.56 to accommodate the longer 62 gr SS109 steel core NATO round. This also means the longer 5.56 chambered guns can shoot longer (and heavier) 224 caliber bullets up to 90 gr and seated out to a COL as long as 2.55" (Sierra). Those are unlikely to fit in a magazine and may require single round loading.

You can also look for 5.56 reloading dies. You wont find any. The cartridge dimensions are the same so only 223 dies are made (and of course work with 5.56 brass and bullets.

[steve4102]

NATO clearly loads there rounds hot and that may be a big reason they require the primers to be crimped .

Naw, chamber pressure has nothing to do with primer crimps. It's a Military thing, rough handling/transport and of course Fully Auto-Matic weapons that can
not afford for a primer to come loose during combat.

As Marco pointed out the 5,56 is not heavier and does not have less case capacity then 223 brass. In fact in most instances the 5.56 has More case capacity.

[243winxb]

At this link you will find data for SAAMI & NATO by pressures. http://www.accuratepowder.com/wp-con...ec_1-23-14.pdf

5.56 X 45MM NATO
CIP COMMERCIAL AND NATO/MIL SPECIFICATION (62,350 PSI)

As far as brass being different, your scale will give you the answer. Check the weight after FL sizing & trimming.

[steve4102]

Originally Posted by 243winxb

As far as brass being different, your scale will give you the answer. Check the weight after FL sizing & trimming.

If you view the link provided by Marco, you will note that there is no direct correlation between case weight and case capacity.

[Bart B.]

The case weight vs capacity table listed in...

http://www.accurateshooter.com/cartridge-guides/223rem/

...is useless as the outside dimensions of each case is not listed. Weight only relates to capacity when the outsife dimensions of all cases are the same. That typically happens at equal peak pressures when the case is pressed hard against the chamber limits.

As the metal percentages in all cartridge brass is virtually equal, at peak pressures, heavier cases will have less internal volume; the case takes up space in the chamber; heavier one more than light ones.

[243winxb]

The rifle chamber has a volume, running from the bolt face to when the bullet seals the bore. Put more mass/matter in the volume, pressure goes up.

[skizzums]

in my experience, 5.56 does have more capacity than .223. but I have have tested on PPU, so oher might be different. but for the OP, short answer, no....there is no problem using the 5.56 brass to reload for your .223. 99.99% likely you wouldn't even have an issue shooting factory loaded 5.56 out of your .223.

[Metal god]

I've yet to find anyone to explain why there is close to no 5.56 data that has more powder or velocity then the 223 data when using the same components .

Well I can't say that any more 243winxb Thanks for that Accurate powder link .

[4runnerman]

i sell 1000's of 223 cases a year. I sort mine by weight and sell the rest. I can tell you this-weight is different and internal case volume is different.
Most NON military 223 case will weigh in at ( sized and deprimed) 91 to 94 gns.
Most military cases will come in 95 to 108 gns. Non military cases-25.5 gns Varget-fill just below shoulder of case- Military cases- 25.5 gns Varget-fill right up to the neck and some more. Now I have had many also ( Military) come in at 91 to 94 gns to,but generally they are heavier. The head stamp has a lot to do with it. I just finished going through 5000 cases in the last 3 weeks. And yes I weighed them one at a time. Picked out what I wanted( 91 to 94 gns). I have about 3000 extra ones left now that I sell to another guy. I load 223 all winter long and shoot all summer long. Just picked up 10 lbs of varget, should get me just short of 3000 rounds,plus I have about 8 lbs already in stock.

[steve4102]

Here is the brass I had on my bench several months ago.

GFL dry weight-102.4gr
With H20-131.4
Case capacity in grains of H20-29gr

Remington Dry weight-95.2gr
With H20-125.1gr
Case capacity in grains of H20-29.9gr

LC Dry weight-96.3gr
With H20-126.7gr
Case capacity in grains of H20-30.4gr.

This brass was all trimmed to length and fired in the same rifle. Case length was the same for each case tested. These were fired, not sized.

Note, that my LC brass weighed more than my Remington brass yet had more case capacity.

I stand by my comment, that there is no direct correlation between case capacity and case weight.

[bledsoeG19]

Hey skizzums, do you have problems resizing PPU brass? Im using rcbs 223 small base dies and I can instantly tell when I get ahold of a PPU case. Very hard to resize.

[skizzums]

no, I love the PPU bras, t's actually my favorite. I find it soft and easy to size. weird. who knows where mine came from though. I have a good bit of it, I would say prob 25% of my cases are ppu

[4runnerman]

Ok here is a picture of Military ( on the right) 96 to 101 gns and non Military (on left). 92 to 94 gns. All 4 cases have 25.5 gn Varget in them. Now while the difference is small keep in mind we are talking small cases here. Hope you can see the difference in load volume. Military cases would be a compressed load. Now while water volume might be the same,As you see dumping powder is not the same. The loads were dumped in each case the same and not tapped to even out. Now this is NOT a scientific test here,but it shows a point. If the brass is anywhere from 3 to 12 gns heavier and outside dimensions are the same, it is wise to assume inside dimensions are not the same. I can not argue the water test , it is what it is, but for the powder test you can see for yourself and you can do this test for yourself as well. Now if you load 25 cases on the right and 25 cases on the left,you will see POI will shift big time. Accuracy also fails ( in my rifle).

[steve4102]

I never assume when it comes to handloading, I always verify.

True case capacity is measured with liquid, usually H20. Visual inspecting of a bulky rat-**** powder like Varget is indeed a poor technique.

[F. Guffey]

New to reloading, I know there is a pressure difference between .223 and 5.56, but is the brass dimensionally the same? My mini 14 and my AR can use either, but I have a bolt action .223 that should only use that load. If I load 5.56 brass as a .223, is it a problem? Thanks in advance.

After firing all of my 223 cases become 223 cases, all 4,000+ of them.

F. Guffey

[Bart B.]

Note that a brand new case will have a certain internal capacity, volume or space. After firing, it's internal space will be bigger. How much depends on the size of the chamber it was fired in as well as how much it shrunk back from chamber dimensions.

When is case capacity at its most meaningful value? When it's new, once fired, resized or during the time when pressure inside it is peaked and its outside surface is pressed hard against the chamber with its outer dimensions are that of the chamber?

[4runnerman]

steve4102-While water is the norm,one can not dispute the powder level either. You seem to have issues with Varget?. Small group you are in there buddy. This test can be done with any powder you would like to try. Ball or stick. Results will be the same. To bad powder don't sit like water in a case.

[steve4102]

Small group you are in there buddy

Not really, Handloader magazine, Rifle magazine, Most of my manuals and especially Quickload recommend measuring case capacity of a "Fired" case in grains of H20. You want to do a visual with a rat-**** powder, be my guest, I will follow Quickload's technique and suffer the consequences of an accurate measurement.

[4runnerman]

steve4102- I meant small group of people that don't like Varget Powder. Now I have never used Quickload and have heard great things about it. I still do my load work up the old fashion way. I use Dan Newberrys way and have always had great luck. Never have found a need for Quick load. Which is just a guesstamation anyhow. Real live results will not be Quick load results by far.
Each to their own I guess.

[steve4102]

Quickload is just another tool and is by no means a substitute for proper load work-up. It will do so many things a manual can't, but it does not replace actual pressure tested data and proper load development, it was never intended to.

[Unclenick]

Caution: Do not use the Western Powders load data for 5.56×45 without a lot of careful consideration

I was very surprised to see the separate 5.56 loads in the Western load data. That data constitutes a significant misunderstanding. After seeing it, I called Western Powders yesterday afternoon and explained what I am about to explain here. The response of the technician I spoke with was “Oh”; and then, “I’ll pass that along.”

There is no difference in absolute pressure between .223 Remington and 5.56 NATO. None! The two different Maximum Average Pressure (MAP) standards are artifacts of the different measuring instrumentation used here and in the CIP. The same lot of reference cartridges put in a SAAMI or a Lake City conformal transducer that gives readings averaging 55,000 psi will give readings averaging 62,366 psi in European channel transducers. This why the U.S. military and SAAMI specs have a maximum average pressure (MAP) of 55,000 psi and the Europeans have a MAP of 62,366 psi (actually, 4300 bar in their units). The European EVPAT 7.62 and 5.56 test procedures are based on results of their measurements of reference ammunition made in the U.S. using the U.S. test procedures, SCATP 7.62 and 5.56 for NATO compatible ammunition.

From MIL-C-9963F, for 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.

3.8 port pressure.

3.8.1 Measurement by copper-crush cylinder. -The average port pressure of the sample cartridges, conditioned at 70° ± 2°F, shall be 15,000 PSI ± 2000 PSI.

3.8.2 Measurement by piezoelectric transducer. -The average port pressure of the sample cartridges, conditioned at 70° ± 2°F, shall be 14,400 PSI ± 2000 PSI.

The piezo transducer in 3.7.2, above is a conformal piezoelectric transducer wherein the head of the piston that presses on the piezoelectric element is machined to match the chamber on the inside. This allows a cartridge to be placed into the chamber whole, and the pressure is measured over top of the brass.

The channel transducers used in Europe have a gas checked piston whose head is exposed directly to the propellant gas with no brass in between. The CIP does this by drilling a hole in the case and lining it up with the piston channel during firing, same as we do for copper crushers. The NATO EVPAT procedure samples the gas just in front of the case mouth to avoid the time consuming drilling and aligning.

The reason for the large size of the difference in readings between the two systems is not entirely clear. The brass interference does not account for it. The conformal transducer, for example, give 62,000 psi for .308 and 7.62 NATO ammunition that was 52,000 CUP in a copper crusher, while the channel transducers gives it only 4150 bar (60,191 psi), actually a lower number. The two systems are complicated by CIP having two different metric piston sizes, by masses not being the same, by electronic filtering being necessary to damp ringing in the EVPAT case mouth readings, which have their pressure applied more suddenly than through a drilled case, and selection of which filtering affects the reading values. It’s a very complex set of interactions and about the only thing you can say for sure is the systems don’t track one another.

The above is why reference ammunition is created. Even just within the SAAMI system, because your pressure tester won’t match mine exactly, even after calibration, one manufacturer is given responsibility for each chambering to load and supply reference ammunition to the industry. The reference cartridges are fired and whatever result you get on your system from them becomes the result you will use for your testing limit. Readings may be scaled to that as a correction factor.

In the case of the Western data for 5.56×45, the error is that they didn’t use channel transducers for the higher pressure limit. They used a conformal transducer. That ammunition would be expected to measure up to 4876 bar (70,719 psi) on the European equipment. Also, like most U.S. handloading data, no port pressure testing is done on the assumption the ammunition will be fired in bolt guns. It is not really NATO compatible ammo without gas port testing.

Will this hurt anything? Well, it’s not reaching proof pressures, which would be a minimum of 134% over MAP or 73,500 psi on a SAAMI conformal transducer. The CIP uses a lower percentage increase for proofing than SAAMI does, 125% over MAP, and that works out to 5375 bar (77,958) on a channel transducer. Brass will be stressed harder at this higher pressure, bolt face erosion and throat erosion will accelerate. Gas gun cycling will be harder.

It is interesting to note that when copper crushers were still in use in the original development and specifications for the cartridge, everything was much closer. This is because the way copper crushers were used by the various organizations was more similar. The copper crusher standards for M193 NATO ball ammunition are:

U.S. military: 52,000 psi (CUP, in SAAMI terminology, as this is by copper crusher)
NATO: 3700 bar (53,366 CUP)

The difference is so small as to be statistically insignificant, given the limited precision of copper crushers. Copper crushers have been phased out of military ammunition making, but the numbers are still valid standards and have not been changed.

The commercial .223 Remington copper crusher standards are:

SAAMI: 52,000 CUP
CIP: 3700 bar (53,366 CUP)

The SAAMI standard carried the U.S. military copper crusher MAP into commercial .223 loads, and the CIP standard carried the NATO copper crusher MAP over to commercial use. The European copper crushers use a slightly different pressure port location and a metric size piston, so the readings would not be expected to be exactly the same, even if copper crushers were perfectly repeatable.


Several years ago I had a phone conversation on the general topic of pressure standards with then SAAMI Technical Director, Ken Green (ret. 2011). The specific subject then was the MAPs for .357 and .44 Magnum cartridges. The original MAPs had been 45,000 CUP and 40,000 CUP for the two cartridges, respectively. But in the conformal Piezo transducer they are rated and 35,000 psi, and 36,000 psi, respectively, a decrease of 10,000 units for the .357 Mag, and if 4,000 units for the .44 Mag. Most every Internet pundit seemed to think this meant the two cartridges had been wimped down from their original pressures over liability concerns. Ken Green told me otherwise. He said the exact same reference loads made up in and used for copper crushers were fired in a Piezo transducer simply produced those different results. The two types of instrumentation just don’t track. Most people would like to believe absolute pressure numbers from these measurements were more exact than they actually are, but SAAMI’s own documentation show the same lots of reference ammunition can give results that vary over 23% in copper crushers and 11% in piezo transducers. This is why the reference ammunition is still necessary to keep people on the same page.

The original development of pressure levels for these rounds was done (see Elmer Keith’s work) until the gun being used said “uncle”, and then were backed off a percentage for a safety margin. They were not developed to an instrumentation standard, but to a gun. The instrumentation was applied subsequently to get a pressure standard that could be duplicated in manufacturing. If the absolute pressure standard had actually been lowered between the copper crusher and Piezo transducer standards, then the CUP’s would have been changed downward, too, and not left where they were. You don’t want a manufacturer still using a copper crusher producing different pressure ammunition than one using Piezo equipment. Again, those same copper crusher numbers are still in force, today. You can read the standards on SAAMI’s web site and see for yourself.

The same applies for the rifle rounds. The original pressures and reference loads remain the same. The Piezo numbers are just what SAAMI Piezo equipment reads them to be. It is the same with the CIP. Their copper crusher numbers remain valid, even though they are considered obsolete, because they represent results from the same reference ammunition. So, an unfortunate result is we have close to matching .223 and 5.56 pressures on everybody’s copper crushers, but not on the different piezo transducers.