Formulas for 5.56 and 223?

Prof Young · January 19, 2021, 11:55 PM

Loaders:

Are formulas for 5.56 and 223 interchangeable?

Life is good.
Prof Young

kmw1954 · January 20, 2021, 01:41 AM

Mostly yes.

Western has it broken down into 223 and 5.56X45 NATO..
Hornady 10 has it broken into 223, 223 Remington Service Rifle and 5.56 NATO

Not sure what the rest of them do as I am using both of those sources presently.

Shadow9mm · January 20, 2021, 08:33 PM

I would not recommend it. 5.56 brass can be thicker giving less case capacity causing higher pressures. Its not much, but it is something. Personally I work up my loads in 5.56 brass, and I know they will be fine in 223....

**Unclenick** · January 20, 2021, 09:18 PM

Shadow9mm,

What you say about lower capacity is true for 7.62 NATO, and to a smaller degree of 30-06 with modern cases (there used to be Peters 30-06 cases that were 215 grains, where Lake City run around 195 grains) currently produced. But all the Lake City 5.56 NATO I have actually has a little more capacity than the common commercial brass. There's a good list of case weights and capacities on 6mmBR.com if you click on their 223 info. The main thing that distinguishes Lake City from non-military brass is the heads are harder.

When you look at CIP Max pressure for 223 Remington, it is the same as SS109, which is 4300 bar (62,366), so if you have bought European 223 that wasn't specially loaded for the US market, your gun has worked at that pressure, according to their instrumentation method. Where you might hesitate to go is to the higher pressures now being loaded by the military for M855A1 and Mk.263 mod.1 for shorter barrels. They have higher pressures than the original M855 and Mk. 263 mod. 0. The higher pressures come from using a faster powder to cut down on muzzle flash in shorter barrels without giving up MV. The military has reported accelerated throat and barrel wear.

So, the recipes should be pretty much interchangeable if they have been established in the same measuring system or in different systems both calibrated to the same lot of reference loads.

rc · January 20, 2021, 09:33 PM

Stuff a case full of AA2230. Make sure it's within spec. Pick Bullet. Load.

zeke · January 20, 2021, 09:54 PM

Pretty sure it's the chamber spec's that may be different, with 5.56 having a longer throat/freebore. So in some cases it may depend on what factors someone is including "a formula" Am in possesion of two 223s cz rifles that will not accept a certain target bullet loaded out to a max COL that easily fit all my 5.56 rifles. Depends where the ogee is on a particular bullet. In this case if you need to load a certain bullet shorter, it may affect the pressure. Am not aware of how all 223 chambers are cut, so it certainly is possible CZ cuts their chambers to a minimum.

If you are checking the max col of the bullet you are using for the chamber of the rifle being loaded for, you would catch this and adjust "formula" accordingly.

**Unclenick** · January 20, 2021, 10:47 PM

The longer freebore in the 7.62 Vs. 308 was intended to make room for specialty bullets; at least, that's what I've read. I assume the same is true of the 5.56. It's hard to be sure, as, after the development was commercialized as. 223 Remington, the military kept altering the chamber for a couple of years to improve feed reliability, too.

Marco Califo · January 21, 2021, 11:22 AM

Starline brass makes 2 kinds of 223 brass. 223 and 5.56. The dimensions are the same, but the case head is harder in the 5.56 version. I load for bolt and and semi-auto rifles. You need to be aware of (measure) your barrel twist rate, and understand your chambers' and magaxines' (COAL).
I bought some ☆-☆ 5.56, but have not weighed or loaded yet. Case capacity is about the same for all headstamps in 223 and 5.56 across brands, and does NOT vary and reduce case capacity the way 308/7.62 milspec LC does. There is a table of case weights in this article: https://www.accurateshooter.com/cart...guides/223rem/
As to load interchangeability, I have worked up max fps and pressure in bolt guns without issue, including the 5.56 data. These Savage barrels are marked 223, but I can detect no difference or pressure signs. Within my my 2 Savage bolt guns, the chambers are different in COAL they will chamber.
Metal God posted this link to an article about the 223/5.56 conundrum: https://www.luckygunner.com/labs/5-56-vs-223/

January 19, 2021, 11:55 PM	#1
Prof Young Senior Member Join Date: August 21, 2007 Location: Illinois - down state Posts: 2,404	Formulas for 5.56 and 223? Loaders: Are formulas for 5.56 and 223 interchangeable? Life is good. Prof Young

January 20, 2021, 08:33 PM	#3
Shadow9mm Senior Member Join Date: March 21, 2012 Location: Indianapolis, IN Posts: 3,974	I would not recommend it. 5.56 brass can be thicker giving less case capacity causing higher pressures. Its not much, but it is something. Personally I work up my loads in 5.56 brass, and I know they will be fine in 223.... __________________ I don't believe in "range fodder" that is why I reload.

January 20, 2021, 09:18 PM	#4
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Shadow9mm, What you say about lower capacity is true for 7.62 NATO, and to a smaller degree of 30-06 with modern cases (there used to be Peters 30-06 cases that were 215 grains, where Lake City run around 195 grains) currently produced. But all the Lake City 5.56 NATO I have actually has a little more capacity than the common commercial brass. There's a good list of case weights and capacities on 6mmBR.com if you click on their 223 info. The main thing that distinguishes Lake City from non-military brass is the heads are harder. When you look at CIP Max pressure for 223 Remington, it is the same as SS109, which is 4300 bar (62,366), so if you have bought European 223 that wasn't specially loaded for the US market, your gun has worked at that pressure, according to their instrumentation method. Where you might hesitate to go is to the higher pressures now being loaded by the military for M855A1 and Mk.263 mod.1 for shorter barrels. They have higher pressures than the original M855 and Mk. 263 mod. 0. The higher pressures come from using a faster powder to cut down on muzzle flash in shorter barrels without giving up MV. The military has reported accelerated throat and barrel wear. So, the recipes should be pretty much interchangeable if they have been established in the same measuring system or in different systems both calibrated to the same lot of reference loads. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 20, 2021, 10:47 PM	#7
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	The longer freebore in the 7.62 Vs. 308 was intended to make room for specialty bullets; at least, that's what I've read. I assume the same is true of the 5.56. It's hard to be sure, as, after the development was commercialized as. 223 Remington, the military kept altering the chamber for a couple of years to improve feed reliability, too. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

January 21, 2021, 11:22 AM	#8
Marco Califo Senior Member Join Date: April 4, 2011 Location: LA (Greater Los Angeles Area) Posts: 2,598	Measure your chambers Starline brass makes 2 kinds of 223 brass. 223 and 5.56. The dimensions are the same, but the case head is harder in the 5.56 version. I load for bolt and and semi-auto rifles. You need to be aware of (measure) your barrel twist rate, and understand your chambers' and magaxines' (COAL). I bought some ☆-☆ 5.56, but have not weighed or loaded yet. Case capacity is about the same for all headstamps in 223 and 5.56 across brands, and does NOT vary and reduce case capacity the way 308/7.62 milspec LC does. There is a table of case weights in this article: https://www.accurateshooter.com/cart...guides/223rem/ As to load interchangeability, I have worked up max fps and pressure in bolt guns without issue, including the 5.56 data. These Savage barrels are marked 223, but I can detect no difference or pressure signs. Within my my 2 Savage bolt guns, the chambers are different in COAL they will chamber. Metal God posted this link to an article about the 223/5.56 conundrum: https://www.luckygunner.com/labs/5-56-vs-223/ __________________ ............ Last edited by Marco Califo; January 24, 2021 at 11:44 PM. Reason: Links

January 20, 2021, 01:41 AM	#2
kmw1954 Senior Member Join Date: June 11, 2016 Location: SE Wisconsin Posts: 1,524	Mostly yes. Western has it broken down into 223 and 5.56X45 NATO.. Hornady 10 has it broken into 223, 223 Remington Service Rifle and 5.56 NATO Not sure what the rest of them do as I am using both of those sources presently.

January 20, 2021, 09:33 PM	#5
rc Senior Member Join Date: April 28, 2001 Location: CA Posts: 1,768	Stuff a case full of AA2230. Make sure it's within spec. Pick Bullet. Load.

January 20, 2021, 09:54 PM	#6
zeke Senior Member Join Date: November 17, 1999 Location: NW Wi Posts: 1,671	Pretty sure it's the chamber spec's that may be different, with 5.56 having a longer throat/freebore. So in some cases it may depend on what factors someone is including "a formula" Am in possesion of two 223s cz rifles that will not accept a certain target bullet loaded out to a max COL that easily fit all my 5.56 rifles. Depends where the ogee is on a particular bullet. In this case if you need to load a certain bullet shorter, it may affect the pressure. Am not aware of how all 223 chambers are cut, so it certainly is possible CZ cuts their chambers to a minimum. If you are checking the max col of the bullet you are using for the chamber of the rifle being loaded for, you would catch this and adjust "formula" accordingly.