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  #1  
Old 01-30-2012, 07:58 AM
Taxesquire Taxesquire is offline
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Different OAL for 5.56 NATO than for .223?




I apologize in advance for posting a question about reloading for a gun other than a 1911, but the AR-15 is in the same extended family.

Anyway, I have been doing research lately as to the difference between .223 ammo and 5.56 NATO ammo, and it appears that they both use the same size shell casing, but the 5.56 tends to have thicker brass and is loaded to higher pressures than .223. As a result, a rifle labeled for either round should handle .223 with no problem, but 5.56 should only be fired from rifles designated for that round, because .223 rifles, especially non AR style rifles, may not be able to handle the pressure of the 5.56. It also appears that the chambers of 5.56 rifles are slightly longer than .223, with the result that .223 ammo tends not to shoot as accurately from a 5.56 chamber as it does from a .223 chamber, because the round is slightly shorter than the chamber.

I have a Colt AR-15 Sporter from around 1990 that, from what I understand, should be chambered for 5.56. My question, then, is that if I reload for this rifle, even if powder charges are kept within .223 specs, should the overall length of the cartridge be longer than for a .223, to more accurately fit the chamber? At the moment, I donít have any reload data for 5.56, so I donít have a reference point on minimum OAL.

Thanks in advance for any information.
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  #2  
Old 01-30-2012, 09:32 AM
mikeg1005 mikeg1005 is offline
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The difference between 5.56 and 223 is in the chambering itself.

223 has a steep angle in the throat... Like such.



5.56 is loaded hotter... Because of this "hotter load" and the increased throat angle in 223, 5.56 ammo in a TRUE 223 will have higher pressure.


NOW....(as far as I know all modern) ARs don't have "true" 223 Remington chambers, they have what is called a 223 wylde chamber(see above).... the 223 Wylde chamber has a less steep throat than a 223 Rem, but not as gradual as 5.56.

Hense why you can shoot both through a 223 or 5.56 chambered AR15.


Mike.
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  #3  
Old 01-30-2012, 09:39 AM
moxie moxie is offline
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Same OAL for both.

Your published reloading data, amd hence any recommended OALs, is all based on the ".223 Remington."
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  #4  
Old 01-30-2012, 10:07 AM
TheTinMan TheTinMan is offline
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The answer to your questions, especially given that you don't know whether your Colt is chambered for .223 or 5.56, is that you need to measure both the headspace and the leade of the chamber in YOUR rifle.

I wrote the following and then realized referring to an expert would be better:
Glen Zediker on AR15 Chambers

OAL depends on your chamber, how long the leade is, and the shape of the particular bullet that you are using. (There is a lot more difference in the shape of bullets with the same weight and general description than most people realize. That's why I always like to start with the bullet manufacturer's spec for OAL if available.)

In an AR-15, the magazine limits OAL. Usually that means your bullet has to jump more than the .003" optimum for a bolt-action rifle. However, a tight "match" chamber might have a very short leade. Seating the bullet so that it actually touches the start of the rifling significantly increases chamber pressure and might be dangerous. Typically, a 5.56 Nato chamber will have a longer leade than a .223 chamber but you need to find out if you want to maximize accuracy.

Hornady's OAL gauge is the best way that I know of to do these measurements, but there are older methods involving a disassembled bolt and dynkem or magic marker.

The other difference between .223 and 5.56 is the headspace. A 5.56 chamber should be longer between the breech face and the datum point where the shoulder is measured. This means that you usually don't push the shoulder back as far when resizing 5.56 as you would for .223. However, headspace varies from rifle to rifle and IRRC the .223 NO GO chamber headspace gauge is longer than the GO 5.56 headspace gauge. IOW the acceptable ranges overlap.

Generally, you want the shoulder .003-.005" shorter than your chamber. Again, you need to measure your chamber (Hornady & others make headspace gauges). Note: spent brass may be bigger than your chamber because extraction occurs while the case is still expanding.

I didn't understand the effect of cartridge headspace on accuracy for a long time - just knew it was important. Basically, a cartridge sized to just fit into the chamber will tend to center the neck & bullet better in relation to the throat of the chamber. If the shoulder is pushed right into the front of the chamber, it's like pushing a cone into a funnel. The other advantage of resizing your brass just enough to fit YOUR chamber is that it works the brass less.

Last edited by TheTinMan; 01-30-2012 at 02:58 PM. Reason: bullet "weight" varies
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  #5  
Old 01-30-2012, 11:37 AM
Nick A Nick A is offline
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For AR-15

Max OAL for an AR15 magazine is 2.260". You can't go longer, it won't fit.

That suits virtually every AR chamber in the entire world.



Of course, reference your data manual for OAL and powder charge.
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  #6  
Old 01-30-2012, 11:47 AM
Nick A Nick A is offline
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For bolt action rifles

Your maximum OAL depends upon your chamber dimensions and your magazine box.
Where it is almost useless to measure an AR chamber
(because the magazine is the limiting factor)
it is generally useful to measure your bolt action 223 Rem chamber and mag box,
especially if you intend to load out to the lands.
(Note: Loading to the lands is often over rated,
unless you max out every other aspect of making a match rifle and ammo.
But that's a different thread.)



Notes from the real world, not everyone will agree:
  • In nearly every case (unless you have a weak rifle) 5.56x45 military loads aren't that much heftier than 223 Remington. No one blows up rifles all day using 5.56 surplus ammo, unless the rifle already has a problem. Check your rifle (or have a smith check it) to make sure it is safe and robust. You'll never have a problem being safe. Certainly, if 5.56mm military ammo scares you, don't buy it. But millions and millions of shooters buy surplus ammo by the truckload and shoot it in every 223 rifle they own. Failures are attributable to the gun, not the ammo. It really isn't that big a deal, unless you make it one.
  • Contrary to popular belief, not all military 5.56 is loaded hotter than SAAMI commercial ammo. It depends upon the purchase order requirements. Much of it is identical to commercial ammo. The important fact is that military contracts don't limit themselves to SAAMI commercial standards, so it can exceed commercial standards and it does so often. As millions and millions of American 223 shooters can testify over 40 or 50 years, surplus ammo doesn't automatically blow up every 223 rifle. But since much of it does exceed commercial standard, it is possible to get shorter barrel life and maybe shorter bolt face life if you give your bolt action rifle an exclusive steady diet of hot 5.56mmx45, even though we don't get reports of that happening much at all.
  • For AR-15 rifles, internet lore has muddied the water unecessarily. They are made to the same standard as M-16 rifles, except for the third position on the selector switch. M-16 and other military chambers are cut differently for extraction in full-auto mode, it has nothing to do with the ammunition itself. Especially since the magazine can only take 2.260" max OAL. That's the limiting factor. Otherwise, AR-15 rifles in good condition are amazingly robust. Check your rifle carefully (or have a smith check it) to make sure it's in good shape.
  • Finally, many many readers since Al Gore's invention of the Internet have become convinced that 5.56 mil ammo is a hand grenade waiting to happen in your 223 chambered AR, and they refuse to believe anything else. With those persons, I won't stand and argue, nor will I wrestle a pig in the mud because the pig enjoys it too much.

Last edited by Nick A; 01-30-2012 at 11:58 AM.
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  #7  
Old 01-30-2012, 12:01 PM
Nick A Nick A is offline
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For all rifles...

All rifles, all calibers, all cartridges:

There are tens of thousands of different bullets on the market.
They all have a different profile over the nose and ogive.

When you buy a different bullet,
always check to see if it fits your chamber safely
at your chosen OAL.

If necessary, make adjustments.

Always do that.
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  #8  
Old 01-30-2012, 12:02 PM
Nick A Nick A is offline
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Final note...

When you reload, you reload 223 Rem when you use 223 Rem data.




You only reload 5.56mmx45 when you use 5.56mmx45 data.




If you reload and use standard 223 data from your data manual, you're good to go.
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  #9  
Old 01-30-2012, 12:05 PM
Nick A Nick A is offline
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5.56 Thicker brass? Hold on there, partner.

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

Read the whole thing.
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  #10  
Old 01-30-2012, 01:36 PM
HughUno HughUno is offline
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Quote:
Originally Posted by Nick A View Post
Notes from the real world, not everyone will agree:
  • In nearly every case (unless you have a weak rifle) 5.56x45 military loads aren't that much heftier than 223 Remington. No one blows up rifles all day using 5.56 surplus ammo, unless the rifle already has a problem. Check your rifle (or have a smith check it) to make sure it is safe and robust. You'll never have a problem being safe. Certainly, if 5.56mm military ammo scares you, don't buy it. But millions and millions of shooters buy surplus ammo by the truckload and shoot it in every 223 rifle they own. Failures are attributable to the gun, not the ammo. It really isn't that big a deal, unless you make it one.
  • Contrary to popular belief, not all military 5.56 is loaded hotter than SAAMI commercial ammo. It depends upon the purchase order requirements. Much of it is identical to commercial ammo. The important fact is that military contracts don't limit themselves to SAAMI commercial standards, so it can exceed commercial standards and it does so often. As millions and millions of American 223 shooters can testify over 40 or 50 years, surplus ammo doesn't automatically blow up every 223 rifle. But since much of it does exceed commercial standard, it is possible to get shorter barrel life and maybe shorter bolt face life if you give your bolt action rifle an exclusive steady diet of hot 5.56mmx45, even though we don't get reports of that happening much at all.
  • For AR-15 rifles, internet lore has muddied the water unecessarily. They are made to the same standard as M-16 rifles, except for the third position on the selector switch. M-16 and other military chambers are cut differently for extraction in full-auto mode, it has nothing to do with the ammunition itself. Especially since the magazine can only take 2.260" max OAL. That's the limiting factor. Otherwise, AR-15 rifles in good condition are amazingly robust. Check your rifle carefully (or have a smith check it) to make sure it's in good shape.
  • Finally, many many readers since Al Gore's invention of the Internet have become convinced that 5.56 mil ammo is a hand grenade waiting to happen in your 223 chambered AR, and they refuse to believe anything else. With those persons, I won't stand and argue, nor will I wrestle a pig in the mud because the pig enjoys it too much.
bless you. copied and stashed for the next pig-wrestling event..
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  #11  
Old 01-30-2012, 03:02 PM
TheTinMan TheTinMan is offline
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Quote:
Originally Posted by Nick A View Post
All rifles, all calibers, all cartridges:

There are tens of thousands of different bullets on the market.
They all have a different profile over the nose and ogive.

When you buy a different bullet,
always check to see if it fits your chamber safely
at your chosen OAL.

If necessary, make adjustments.

Always do that.
Much shorter and more to the point than my needlessly long post.

Quote:
Originally Posted by Nick A View Post
Go here http://www.6mmbr.com/223rem.html.

Read the whole thing.
Read it. Liked it. Bookmarked it.

Thanks Nick.
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  #12  
Old 01-30-2012, 06:32 PM
herd48 herd48 is offline
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Nick- I saw this thread early this morning. I thought to myself, where to begin. Some really inaccurate and confusing info early on. Inaccurate on a practical sense for sure. I wish I had your patience and diplomatic skills. I didn't have the time or desire at 5am. Thanks
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  #13  
Old 01-30-2012, 08:28 PM
Nick A Nick A is offline
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You're east coast, brother herd. I'm west coast.
We get an extra 3 hours of sleep.

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  #14  
Old 01-30-2012, 09:35 PM
Steve4102 Steve4102 is offline
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The 5.56 is not thicker and does not have less case capacity than 223 brass. This is a myth that will not die as many handloaders believe what holds true for the Military 308 Win and 30-06 also holds true for the 223/5.56. It does not.

Quote:
It also appears that the chambers of 5.56 rifles are slightly longer than .223,
This is also not entirely correct. The 223 and the 5.56 has basically identical chamber lengths. Here are the specs for a few different 223 and 5.56 reamers.
http://ar15barrels.com/data/223-556.pdf

As you can see the "chamber" dimensions "K" are almost identical except for the 223 Rem Match witch is a bit shorter. The throat/freebore "N" varies quite a bit between reamer manufacturers with the 223 Rem Match being the longest at .0680.
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  #15  
Old 01-31-2012, 07:42 AM
Taxesquire Taxesquire is offline
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Thanks very much to all of you for the information, which I will certainly study with care. However, I think my REAL questions, which I should have posted earlier, have been answered.

My intention is to load using only .223 published data, both to eliminate any issue as to excess pressure, and to avoid needless stress on the brass and the rifle, since I only shoot the AR for fun.

My question as to OAL was to determine whether there would be any noticable increase in accuracy by loading slightly longer, assuming the rifle is chambered for 5.56. Truth be known, however, I doubt seriously that I am a good enough shot for it to make any difference.

Finally, as to case thickness, what I was looking for was information as to whether I should focus on accumulating .223 brass or 5.56 brass, or whether they need to be kept separate. Again, I shoot just for fun, and the extra measures employed by benchrest shooters to ensure absolute consistency in rounds is beyond what I need at this point.

Again, thanks to all for the great information.
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  #16  
Old 01-31-2012, 08:35 AM
Steve4102 Steve4102 is offline
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Quote:
Originally Posted by Taxesquire View Post

My intention is to load using only .223 published data, both to eliminate any issue as to excess pressure, and to avoid needless stress on the brass and the rifle, since I only shoot the AR for fun.

My question as to OAL was to determine whether there would be any noticable increase in accuracy by loading slightly longer, assuming the rifle is chambered for 5.56. Truth be known, however, I doubt seriously that I am a good enough shot for it to make any difference.

Finally, as to case thickness, what I was looking for was information as to whether I should focus on accumulating .223 brass or 5.56 brass, or whether they need to be kept separate.
Most all data is for the 223. Very little data for the higher pressure 5.56. The only place I have seen actual 62K pressure data is from Ramshot. here.
http://www.ramshot.com/wp-content/up...dgun_rifle.pdf

Unless you are going to load single shot the longest you can load in either 5.56 or 223 chamber is 2.260. Start there as long as you have about one diameter of bullet seated. Reducing OAL from 2.260 may find a "sweet spot" for accuracy. Range time and testing is the only way to determine what is the most accurate OAL for any particular bullet. Loading long is not always the most accurate.

Get them both, they will both work just fine. For accuracy some separate brass by headstamp whether it is 5.56 or 223. For plinking ammo doesn't matter.
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  #17  
Old 01-31-2012, 11:19 AM
Nick A Nick A is offline
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5.56 brass vs. 223 Rem brass.

OK, here's the deal.

They all have the same wall thickness
within a thousandth of an inch,
not enough to affect case capacity.

The difference is in the thickness of the web
(that's the base where the flash hole is drilled).

But some commercial is thicker at the web,
and some milsurp is thicker at the web,
so you can't tell by headstamp.
You can tell by weight AFTER sizing and trimming.
But that's often irrelevant unless you're loading max load.

You will find that many maximum loads fill the entire case.
You have to crunch the bullet on top to seat it.
For many max loads, the brass with thicker web
will actually overflow the powder,
not enough case capacity for max load.
Those cases get aside and either:
Adjust powder charge for the same velocity;
Or save them for reduced loads later;
Or save them for heavier bullets that use less powder;
Or switch to a powder that doesn't fill the case.

The distinction will not be 556 vs 223
but actual case capacity.

[In my old age I now select bullet weights
and use powders and charges
that only fill the case to the shoulder,
while still giving me excellent accuracy,
and thus are completely insensitive to headstamp.
This is probably what taxesquire will do with his plinking ammo.]
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  #18  
Old 01-31-2012, 11:41 AM
WalterGC WalterGC is offline
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Most ARs aren't chambered in .223 Wylde...only a relative few. Most ARs are chambered in 5.56, with some being chambered for .223. We're talking about three different chamberings.

5.56 brass isn't thicker than .223 brass and isn't loaded any differently, whether for .223 (it becomes .223 when you run it through a .223 die) or 5.56 or .223 Wylde chambers.
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Last edited by WalterGC; 01-31-2012 at 11:47 AM.
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  #19  
Old 01-31-2012, 10:06 PM
moxie moxie is offline
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From a reloading pespective, the only meaningful difference between .223 cases and 5.56 (military) cases is the crimped primer pocket on the 5.56. This requires swaging via a separate die used in your press (RCBS), a separate tool (Dillon) or reaming gadgets from several manufacturers. I use the RCBS as it's one of the cheapest solutions and works OK. It's a pain but has to be done. I load totally mixed brass in a batch. Both .223 and 5.56, many, many headstamps, whatever I scarf up at the range. Policing up brass is a geography and history lesson in itself sometimes. They all work. The fact that they fired once without incident sort of tells you they work.
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