223 Remington vs 5.56x45mm reloading help

Discussion in 'The Ammo & Reloading Forum' started by mtls44555, Feb 26, 2012.

  1. graehaven

    graehaven Well-Known Member

    May 26, 2007
    Rochester, NY
  2. steve4102

    steve4102 Former Guest

    Jan 27, 2006
    Before you go and arbitrarily reduce charges by XX% because of something you read on the internet, you need to check a few things.

    The first is the link posted by CPT. In this article you will see that in fact the 5.56 Military brass has MORE case capacity than 223 Civilian brass.

    More case capacity coupled with a 10% reduction in "Start" charge is a recipe for disaster. Do NOT DO IT!

    Here is a good article by Sierra on the subject.

    The conventional wisdom to reduce loads with military brass is familiar to most reloaders and is generally good advice. The rationale here is that the military cases tend to be somewhat thicker and heavier than their civilian counterparts, which in turn reduces capacity and raises pressures. This additional pressure normally requires a one or two grain reduction from the loads shown in most manuals or other data developed with commercial cases. While this is most often the situation with both 308 Winchester and 30-06 cases, it is less true with the 223 brass. We have found that military cases often have significantly more capacity than several brands of commercial brass. Again, take the time to do a side-by-side comparison of the cases you are working with and adjust your load as needed. There may be no need for such a reduction with the 223. Know your components and keep them segregated accordingly.


  3. steve4102

    steve4102 Former Guest

    Jan 27, 2006
    This is all wrong. Beside the fact that you have the case capacity backwards, 5.56 load data runs at a higher pressure than 223 data. 5.56 data is few and far between, but it is available from Western Powders. Their 5.56 data runs at 62K psi while their 223 data runs at 55K psi.

    Starting out with 62K 5.56 data in a 223 case(less capacity) in a 223 chambered rifle may not be such a good idea. Best to load for the specific chamber instead of the brass headstamp. Then you can determine case capacity and if you need to adjust accordingly.
  4. time2shoot

    time2shoot Well-Known Member Supporting Member

    Jan 17, 2012
    Brandon SD
    One thing everyone has not said is, powder type.
    You allso need to know where the burn rate is at for the powder you intend to use.
    That alone can cause majer presher diffrences.

    I'll use my 300 winmag. for an example: I reload 150 gr green tip. on top of 71gr. of H414. now this is around 90% case capasaty. and does not couse any over presher ishues.
    I started out loading 67.5 grns. at around 85% capacaty. was saposed to be the most acuret load for this combo. this load was cousing pierced primers and split brass necks.
    Do to the burn rate of H414. it would couse extr presher do to the empty volume of space. So once again we get back to case cap.
    So all in all you need to take into consideration not only case Cap.but burn rate of your powder being used aswell.
    This is just my opinion on what I have exp. While reloading do to trial and errer.
    Hope this helps thoughs wondering.
  5. dodge

    dodge New Member

    Aug 3, 2010
    ok now that i'm totally confused, my son got me a bunch of brass from his work as a security guard, after they shot. the boxes say 5.56 77 gr. sierra hp made by black hills ammunition. he wants me to reload them for his ar-15 which the barrel says will shoot either .223 or 5.56. i would also like to shoot some in my encore .223. now looking back at some comments on here they state that the 5.56 cases are thicker , so that being said i weighed a buch of the cases , and also some .223 cases and they all weighed pretty much the same, around 93.5 to 95.2 grs. now would'nt the 5.56 weigh more seeing that they are thicker? also would i have to go by nato loading data and then reduce that to shoot in a .223 barrel? any comments would be appriciated. ----thanks
  6. cwbys4evr

    cwbys4evr New Member

    Feb 11, 2013
    Don't shoot 5.56 in your rifle unless it is chambered for 5.56. Second , I would be leery of giving anyone my loads to shoot, especially a loved one. Maybe that's just me, but if something by chance went wrong with something I loaded and hurt someone, I would feel horrible.
  7. salvageer

    salvageer Member

    Aug 21, 2013
    Very good article. I have read it before in search for the difference between 556 and 223. What I get out of all this is there really isn't enough differences to matter. In reloading just load with the lowest suggested amount of powder and work up to the desired load.

    In the article he says "Does this mean that everyone should start firing 5.56 in their .223 chambers? No." But then goes on to say " I have owned approximately sixty AR-15 barrels, with a fairly even distribution of .223 and 5.56 chambers, plus Noveske and .223 Wylde chambers. I have also owned numerous bolt action rifles chambered in .223 Remington. I have fired .223 and 5.56 ammunition in most of these barrels and rifles."
    He's only covering his butt in the first quote. A disclaimer so he doesn't get sued by some goober that builds up a hot load and hurts himself.

    Before the internet information age I never put much thought into it. If it said 223 or 556 on the box. Either shot well in my 3 Ar's, 2 mini 14's and Savage bolt.

    I'm about to get started reloading 223/556 for myself. I am not going to concern myself with any minor differences. I'm just plan do as mentioned above, start at the bottom of the scale and work up. Testing on a chronograph as I go.
  8. RustyFN

    RustyFN Member

    Oct 2, 2008
    West Virginia
    You just proved to yourself that the 5.56 cases are not thicker and have less case volume. I find them to be pretty much the same and load them the same. Do not reduce below the minimum load recommendation. Start at the starting load and work up.
  9. I have a .223 handi-rifle (bull barrel) and shot some 5.56 and had a few popped primers.
  10. Edward Horton

    Edward Horton New Member

    Sep 1, 2009
    I have 2 AR15s and a Savage .223 with a 1 in 9 twist and it has a longer throat than my AR15 rifles.

    Below are the dimensions for .223 and 5.56 chambers, see line N on chart.


    Below on the left is the "short" .0250 throat for .223 rifles with a 1in14 or 1in12 twist.
    On the right is the longer M16/AR15 throat at .0500 and twice as long as "some" .223 throats.


    Below is the mil-spec requirement for the newer 5.56 M885 ammunition with a chamber pressure of 55,000 psi. (US SAAMI pressure standards)
    Please note the .223 and 5.56 are both loaded to 52,000 cup or 55,000 psi and the only difference is the throat length.


    Below is a chart from the link the OP posted, the far left green bar is factory .223 ammunition fired in a .223 rifle. The chamber pressure is over 5,000 psi lower than the max rated pressure of 55,000 psi.

    Now look at the far right blue bar of a 5.56 cartridge fired in a 20 inch AR15 and the pressure is 55,000 psi


    Bottom line if a M885 5.56 ammunition is fired in a short throated .223 rifle the chamber pressure will be approximately 5,000 psi higher than the max rated pressure of 55,000 psi.

    Also note that some newer .223 rifles have throats longer than .0250 and 1in9 twist for shooting heavier bullets. The throat length on my factory Savage .223 is approximately .0566 and it has a 1in9 twist for longer and heavier bullets. Nothing is written in stone and todays rifle chambers have to be able to chamber a cartridge and also have room for the company lawyer.
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