.223 service rifle

[CS86]

I have a good understanding of the difference between .223 and 5.56, but a friend and I are trying to figure something out in the Hornady manual.

Cross referencing load data in the Hornady manual between the .223rem, .223rem service rifle, and 5.56 nato is a bit confusing. We are trying to figure out what the loads in .223rem service rifle are designed for and what they aren't designed for. He just got an AR .223/5.56 and I've only used the .223 data for light grain bullets in a bolt action.

Another question I had is how does one tell the difference of the brass if it isn't stamped .223 or 5.56? Can you weight it and get an accurate figure?

[FrankenMauser]

If it's stamped, it says what it is. If it isn't stamped, assume it's military brass.


.223 Rem "Service Rifle" load data is intended for semi auto rifles - primarily AR-15s.
You can run the loads in a 5.56 chamber without issue.

[chris in va]

The majority of 5.56 cases I've seen at the range are Lake City and are stamped LC and have a date code, such as '08'.

[Jimro]

I have a good understanding of the difference between .223 and 5.56, but a friend and I are trying to figure something out in the Hornady manual.

Cross referencing load data in the Hornady manual between the .223rem, .223rem service rifle, and 5.56 nato is a bit confusing. We are trying to figure out what the loads in .223rem service rifle are designed for and what they aren't designed for. He just got an AR .223/5.56 and I've only used the .223 data for light grain bullets in a bolt action.

Another question I had is how does one tell the difference of the brass if it isn't stamped .223 or 5.56? Can you weight it and get an accurate figure?

223 Rem "Service Rifle" means a 20" AR-15 with rifle length gas tube, and with a SAAMI 223 Rem chamber.

The 5.56 NATO loads are kind of a misnomer as NATO specifications call for crimped primers, so what that means is that the loads are tested to safe in a 5.56 NATO chamber (same headspace as a 223, longer and shallower leade).

You can see a collection of different leade variations between different reamers here:
http://www.radomski.us/njhp/cart_tech.htm

All of this is academic, as long as you do a normal load workup you'll be safe with your rifle.

Personally I'm using a Wylde chamber in my service rifle upper, although I might go with a 223 CLE chamber down the road.

Jimro

[steve4102]

The basic different is the rifles chamber. The 5.56 has a longer lead giving the bullet more jump to the lands. This longer jump allows for the 5.56 ammo to be loaded to higher pressure.

223 load data is tested at a Max Average Pressure of 55K psi. True 5.56 load data is tested at a Max Average Pressure of 62K psi.

As far as I know there is only one source of True 5.56 pressure tested data, that would be Ramshot/Accurate data found here.
http://www.ramshot.com/wp-content/up...ec_1-23-14.pdf

All other data even "Service Rifle" data is tested to 223 pressures of 55K not 5.56 pressures of 62K.

[243winxb]

Another question I had is how does one tell the difference of the brass if it isn't stamped .223 or 5.56? Can you weight it and get an accurate figure?

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

[RC20]

Quick answer on the brass is it will have two or three letters and a date on it if its military.

Civilian brass, will have the caliber (223/308) on it as well as a couple of letters of the mfg on it or it may have the full name (Hornady). Letters may go to 3 (PMC) etc.

5.56 brass is not worth messing (my opinion) with due to the crimped primer removal need (though some do)

[Jimro]

223 load data is tested at a Max Average Pressure of 55K psi. True 5.56 load data is tested at a Max Average Pressure of 62K psi.

This is a true, but meaningless statement.

There is no pressure difference caused by a load difference, only firing the same load in different chambers. SAAMI doesn't specify a 5.56 NATO pressure, but CIP does. CIP simply uses the same load in both chambers. CIP NATO spec is around 58k PSI by their method of measurement, and CIP 223 REM spec is around 62k by the same method due to firing the round in a chamber with a shorter leade with sharper angle. I looked up the CIP chamber dimensions to see what they used.

The spec'd pressure for M193 was actually 53K PSI by SAAMI test method.

Most of the "pressure signs" associated with an overpressure event in an AR, such as a popped primer, are often due to a gas timing issue. Using a powder on the slow side for the projectile is a known cause of a secondary pressure spike which can also show pressure signs even though it is an ammunition defect and not a chamber issue.

So do the load workup in your rifle, once you achieve accuracy and velocity you are happy with, stop. No point in pushing the envelope. If you don't get the accuracy and velocity you want, switch components until you do.

Jimro

[steve4102]

This is a true, but meaningless statement.

There is no pressure difference caused by a load difference, only firing the same load in different chambers.

Really?

Have you looked at actual 5.56 Load Data?

Go here and check it out, then get back to me on how there is no pressure difference caused by load difference.

http://www.ramshot.com/wp-content/up...ec_1-23-14.pdf

[243winxb]

1. In Firearms Chambered For -223 Remington
   
2. Do Not Use These Cartridges - 5.56mm Military
   222 Remington
   25-45 Sharps
   30 Carbine
   300 AAC Blackout

http://www.saami.org/specifications_...mbinations.pdf [IMG][/IMG] [IMG][ When reloading, sort brass by weight. Brass that is on the heavy side may need less powder if loading near maximum pressures.

[steve4102]

Why does "Factory" ammo always get brought into the mix when the when the original post is about handloads?

[Jimro]

Steve4102,

I explained how CIP measures pressure. They use the same 5.56 NATO load in a NATO chamber and measure 58k and then in a 223 Chamber and measure 62k. The difference between a CIP 223 chamber is less than 3 seconds of angle on the leade compared to the SAAMI referrence chamber.

The M193 pressure spec was 53k by SAAMI standards. Even M855 was only 55k by SAAMI measurements. Of course if you put those into a 223 chamber, expect a 4k PSI increase.

You can overload a 223 and call it "NATO" spec by running it through a 5.56 NATO chamber, the FBI did this when they spec'd a 223 load to 62k as measured by SAAMI specs. That level of pressure, measured by that method, is not something I'd run through my rifles. But the truth is that if are measureing to 62K by CIP methods, that involves drilling through the chamber wall, through the brass, and exposing the sensor directly to the gasses generated during firing. This method always measures more pressure than the SAAMI method, so if you say, well we'll load to 62k like the Europeans and measure your pressure the SAAMI way (like the FBI did) you end up with proof load level ammunition. I know of no firearm in existence that can survive on a steady diet of proof loads.

That a powder manufacturer has different load data for 223 and 5.56 isn't surprising, they are different chambers after all. But the testing done by CIP doesn't differentiate between the ammunition, only the chambers.

I hope that clears up any confusion you may have.

Jimro

[Jimro]

243winxb,

The "circle cross" is a "NATO design mark" and not a guarantee of NATO interoperability. It simply means that the ammunition is nominally the correct dimensions, however as DTIC has noted, this is no guarantee that one countries ammo will function in another countries weapons. The prohibition of using American M855 or M855A1 in a Brit L85 is a well known example of this.

There is a variation of a "cloverleaf cross" which is the NATO symbol for interoperability.

http://www.dtic.mil/ndia/2011smallar...Pellegrino.pdf

Jimro

[243winxb]

The Nato stamp tells me its military brass with a crimped in primer. The crimp needs to be removed before reloading. There is other non-Nato marked brass that also may have a crimped in primer. Brass weight is an important factor for a reloader of the 223/5.56 cartridge when loading to maximum pressure. Just how i see it. IMO.

[Jimro]

243winxb,

That is true, the NATO design spec calls for primer crimping. Non NATO countries that use 5.56 like Israel, South Africa, Malaysia, Guatemala, etc have no requirement to stamp their brass with the circle cross, although I do know that IMI does when manufacturing ammunition under contract for the DOD.

Anytime you are loading to max, component uniformity is pretty darn important.

Jimro

[steve4102]

Here is a pressure test done by Barnes.
Note the 5.56 vs 223 pressure difference.



Link
http://www.luckygunner.com/labs/5-56...a-6%2F26%2F12-

[Bart B.]

Steve, what's the actual bore and groove diameters as well as bore cross sectional areas of those test barrels? All I see in the site is chamber dimensions.

If one's got smaller numbers, it'll produce higher pressures with a given cartridge.

[steve4102]

Steve, what's the actual bore and groove diameters as well as bore cross sectional areas of those test barrels? All I see in the site is chamber dimensions.

If one's got smaller numbers, it'll produce higher pressures with a given cartridge.

Good question. You have the link, ask the author or contact Barnes and report back. I'll be curious to know the difference if any.

[Jimro]

Steve4102,

To save some time, why don't you read this thread: http://thefiringline.com/forums/showthread.php?t=541237

Then if you have any issues with anything I wrote here, or there, let me know.

Jimro

[Bart B.]

Steve, you originated that link into this thread. You contact them and ask about bore and groove dimensions. Then you'll get all the glory of finding and sharing all the good information to everyone. You should have been curious enough to ask about that missing info that's so important to pressure number comparisons between two barrels.

[steve4102]

Steve, you originated that link into this thread. You contact them and ask about bore and groove dimensions. Then you'll get all the glory of finding and sharing all the good information to everyone. You should have been curious enough to ask about that missing info that's so important to pressure number comparisons between two barrels.

Good one.

Naw, that's OK, I trust Barnes to include any difference that would be relevant to their Pressure Data. If you don't by all means contact them yourself.

[jr05]

If you are reloading and working up from a low load using a chronograph there is no reason to not use 556 "military" brass in a 223 chambered gun.

I have found it increasingly hard to not find crimped primers even in a lot of the commercial ammunition anyway so dealing with a crimp is not a big deal, not to mention you only have to do it once.

[Jimro]

Steve4102,

To be clear, the Western Powder loading guide is missing some important data.

These two pressures represent the exact same load data.

CIP Maximum pressure (EPVAT) 430.00 MPa (62,366 psi)
SAAMI Maximum pressure (SCATP 5.56) 380.00 MPa (55,114 psi)

SAAMI 5.56x45 NATO pressure has always been 55k psi from a 5.56x45 chamber, as you saw with the luckygunner article, pushing that same 5.56x45 load through a 223 chamber can raise pressure to near the 60k psi range. This is why CIP specifies 223 Rem ammunition to 62k, because they are using the same load data as 5.56x45.

Anyways, when you test a 5.56x45 round with the CIP method in a 5.56x45 chamber, pressure should be 58k psi, and in a 223 Rem chamber 62k.

So that 5.56x45 NATO data in the Western data book SHOULD be pressure specs measured in the CIP method and fired through 223 REM chambers. No guarantee they did it that way though, so as always do a load workup and watch for pressure signs.

Jimro

[CS86]

Good info and references. I haven't had a chance to get back here and see half of the posts, but I'll have to go back and digest what I can. Thanks for all the posts.