223 vs 5.56 ?

And then there is the .223 Wylde. We recently hired a competition 600 m shooter (not to do that, he has just done that for 30 years) and I now have one of those barrels on order as I have never liked mine. I went with 4 grooves and 1:8. Shilen, Ordered it at the NRA convention.

I'm going to be loading .223 to get a heavier bullet, I was hoping to avoid that but I have a 650 on loan and am flat out of bullets for everything else. My 68 lbs. of Xtreme should have been here yesterday.

BTW, I poked Xtreme about delivery at the convention. I said I know folks are coming by and giving you an ear full, I'd rather get a do-over and order more bullets. They gave me a T-shirt.

Glade to see an old question from a new guy here (Edit: well 2,000 posts new - if I hit 1,000 I'm setting up a new login lest people think I actually know anything).

Good luck and don't blow yourself up. I feel I should tell you that - and to buy a reloading book. We here always tell new people to buy a reloading book and not to blow yourself up, THAT apparently never gets old.;)
 
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Just to be sure we don't mislead any newbies reading the thread anonymously, to reiterate, there are no differences in the exterior maximum dimensions of 223 Rem and 5.56 NATO cases. None. The same die that resizes one will therefore resize the other. The only book difference is in the length tolerance, IIRC, with the military using a unliateral tolerance of -0.015", and SAAMI using -0.030". SAMMI used to use -0.020", as shown in their 1992 Standard available for download and same as is used in most of their rifle cartridge standards, but it was widened when the drawing on their web site was updated. I don't know the reason.

For those interested in some of the non-SAAMI chamber dimensions, there is a good comparison at AR15barrels.com.
 
I haven't noticed that the primer pocket dimensions are different in military brass. They crimp non-match cases after seating a primer, but if you buy military brass that has never been loaded previously, it has no crimp and the pockets are the same and accept commercial primers just fine. The military has historically specified internal head thickness and provide a hardness profile for testing sectioned cases, though I don't know if ATK's changes in 2012 affected that.
 
A hefty portion of the market consists of imported or surplus ammo--like PPU privi-partizan--that is made to NATO specs and usually has a crimped and sealed primer. In fact, I've experienced just the opposite--some 223 non Nato-headstamped ammo that was marketed as plain jane ammo but still had crimped and sealed primers.
 
NATO type ammo usually will have a swage/crimp and seal of some sort to make the primer more resistant to the "elements." This might result in a pocket of slightly different dimensions after firing and swaging/reaming.
 
The crimp was actually added in the 1920's because they had problems with primers popping out of their pockets in some of the machine guns they had then which started extraction before pressure was completely gone. The primers would fall into the mechanism and jam the gun. The lacquer primer sealant is what keeps the elements out. Adding it is a separate step.

If you buy new military brass that has never been crimped, pocket dimensions are the same as for commercial small rifle primers. It has to be, so it can be primed. Usually around 0.1745" for press fitting the primer cup in. The specifications for the case are written for what it is prior to loading and crimping, and not for reloading, which the military does not do. Hence, the specification for the primer pocket will be for its new, uncrimped condition, and therefore will match that of commercial primers at that point. Swaging or reaming can distort them if you don't do it well, but at the time of manufacture the swage isn't there yet, so the drawing dimensions will not show a difference from SAAMI.
 
I recycle all my 223/5.56 brass--not only into new 223 cartridges, but 300BO and 25 x 45 as well. Whatever the reasons--I've found that it's mandatory to sort the brass and then uniform and swage the primer pockets--way way too much variation in the pockets.
 
The commercial pockets and primers have diameter tolerance ranges that can accumulate to almost 0.0018" difference in the interference fit of a primer into a primer pocket. That's more than enough to feel very different with a hand priming tool. But they all have the same diameter middle value specification of 0.1740" for pockets. It's just that the specifications tolerances are loose enough for the pockets and primers combined to be allowed to randomly move around some as tooling ages and other factors get involved.
 
Unclenick said:
All this has caused a lot of confusion, as you might imagine.
Click to expand...

Thanks for the detailed explanation about the pressure ratings and so called differences.

To add to the confusion we also have our Loading manuals that have load data for both the 223 and the 5.56.

Take Nosler #7 for example, they have a 223 page and a 5.56 page.

This could be interpreted by those that believe the pressures are indeed different, as meaning that Nosler, like Western, has two different set of pressure standards for the two different cartridges.

223 data.
http://www.nosler.com/nosler-load-data/223-remington/

5.56 data
http://www.nosler.com/nosler-load-data/556x45-nato/

...but if you look close, you will see that the load data on the 223 page is the exact same data as on the 5.56 page. So why the difference and why the two separate sets of data if they are identical (which they are)?

Well, if we click on the "Cartridge Information" button, we will see why.

"Click"

http://www.nosler.com/556x45-nato

TECHNICAL INFORMATION:

The 5.56x45mm NATO cartridge was developed for military use over 50 years ago, and became known as the 223 Remington only when introduced as a commercial round by Remington. Military use notwithstanding, the “5.56” enjoys widespread civilian use in AR-15 style rifles, and is the mainstay of service rifle match competition. Because of the fast-twist rifling used in the 5.56, it will stabilize bullets of up to 80 grains when fired from a 1-8” or faster barrel. Our 80 grain Custom Competition bullet is an excellent choice for extremely long range shooting, but must be fired as a single shot cartridge (this bullet cannot be loaded to magazine length). For magazine length loading in the 5.56, the 69 grain and 77 grain Custom Competition products are excellent choices. If your brass originally had crimped primers, the crimp MUST be removed prior to re-priming. Also, as it is usually necessary to crimp the bullet in place when loading for a semi-auto use, we recommend using a taper crimp. Crimping with a standard seating die (roll crimping) on bullets without a crimping groove can adversely affect accuracy. The data listed in the load data section is safe for use in both 223 Remington and 5.56x45mm cartridges and chambers.

So, according to Nosler data the difference is in reference to Barrel Twist and not chamber pressure.

...and the chamber pressures between their 223 and their 5.56 are the same.

Problem is, far to many handloaders are of the camp that the 5.56 is loaded hotter than the 223 and when they see the two separate data pages they assume that 5.56 data is unsafe in a 223.
 
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