Home Forums Hunting & Shooting Hunter's Campfire 5.56 versus .223 pressures

I have three rifles chambered in 5.56 NATO. Why can’t I reload .223 casings to the same pressures and velocity.? I would like to be getting around 3000 ft./s with 62 grain cup And core soft points.

They are the same.

https://www.luckygunner.com/labs/5-56-vs-223/?utm_source=Newsletter&utm_campaign=349674f69a-6%2F26%2F12-

The difference is in the chamber dimensions, not the brass. The primary difference is the 5.56 NATO chamber has a slightly longer throat to lower chamber pressure compared to the .223 chamber.
There should be no problem loading .223 stamped brass to 5.56 NATO pressure as long as you fire it in a 5.56 NATO chamber.

You can and I do. I like benchmark for 50-60 grain bullets. I just load them up the usual way, till I see pressure signs. My 223 loads are well beyond book loads, probably 150 FPS faster than book loads.

true of the .308 and 7.52x51 too.

I have a Weatherby Vanguard2 in .223 caliber and a 5.56 AR. A friend of mine who usually knows what he is talking about told me that a bolt gun in .223 can handle my 5.56 loads without a problem. He says it is only with semi-auto that there might be an issue. Is this true?

What rifles?

I've loaded untold thousands of .223 over the years,....shot them in AR's, TC Contenders, Ruger 77s, H&R Handi Rifles, Mini 14's, and probably some others that I've forgotten.

I make no distinction between .223 and 5.56.

Chamber and throat dimensions vary between manufacturers at least as much as they do between .223 and 5.56 industry standards.

Bristoe is correct. I can mix and match with my bolt rifle and AR.

Millions of rounds are fired by millions of people every year without any sort of issue.

I've never really heard a valid issue from firing one in the other.

Then we throw in the .223 Wylde.... Just for grins.

And if you worry about such things and can't decide there's the Wylde chambering.

"A .223 Wylde chamber is a hybrid rifle chamber designed to allow .22 caliber barrels to safely fire either .223 Remington or 5.56x45mm NATO ammunition. " wiki

And my CZ 527s all say both are fine. From the factory

AR's, Bolts, Mini14's T/C, doesn't seem to matter .223 or 5.56 factory or reloads, over 35 years now and I can't even recall a flattened primer, much less a real problem
I know I have read it does, but the in early '80s in a gunsmith class with several older fella's that had probably forgotten more about firearms than I know told me it really didn't matter, apparently they were correct.

If you have a .223 chamber stick with .223 ammo. (55,000 psi) Like others have said, it's the chamber and not so much the ammo. No a bolt .223 may not be able to handle the pressure of a 5.56 (62,300 psi) and it just isn't about semi auto vs. bolt action. A bolt action can have a .223 or a 5.56 chamber just like a semi auto can have a .223 or a 5.56 chamber. Your buddy needs to re-think this.

kwg

Two AR's and Ruger American... the bolt gun is the one I want to load 5.56 pressure for.

The real question is, 62 kpsi by whose standard?

NATO 5.56 is nominally 62 kpsi, but the standard, which includes pressure measurement methods, is EPVAT. EPVAT pressure measurement is similar to that used in CIP (but not the same).

The US military does not adhere to the EPVAT standard, but rather employs the SCATP standard. SCATP prescribes the very same pressure measurement methods utilized by SAAMI. The highest pressures in any spec (and I mean actual US military documents) I have been able to locate are about 58,600 psi (IIRC).

I am not too concerned about .223 ammo being loaded to about 58000 psi (and I'm talking SAAMI, as we usually speak of pressures) , but I am not so sure I'd want to push any handloaded ammo much beyond 58000 psi.

Can .223 brass handle 62000 (SAAMI) psi repeatedly? Maybe, maybe not. Can it handle 62000 (CIP or EPVAT) psi? Evidently it can. But those pressure levels should translate to well under 60000 psi per SAAMI methods.

Now, this is all based on information I have been able to dig up over the last six or eight years, and not just data in the Western Powders reloading guide. I am referring to US Military documents. There MAY be documents I have yet to see, where pressures (SCATP) exceed 58600 psi. When I see them, I'll believe them. Until then...nope.

The longer throat and longer minimum headspace in the 5.56 are about full auto reliability with a range of specialty ammo. The pressure difference due to the chamber differences are all well under SAAMI lot variation allowances. The cases have identical exterior dimensions.

The test barrels probably reflect the differences, but will be their respective minimums. The military also includes a gas port pressure range that has to be met and they allow less velocity variation for a given bullet weight than SAAMI. As a result, military ammo is usually kept a little more carefully near the rating maximums than commercial ammo is.

Hello River
This is information I have scrounged via the internet. I try to get the best information just like you do. I understood that the 5.56 max pressure to be the 62,300 psi. In the stuff I read I did not see kpsi. I'm not familiar with what the k stands for. I do use a SAAMI published number to translate pressure from CUP to PSI. It's CUP x 1.52 -18000. If you have a link to the "k" portion I'd be interested in seeing it. Since I use Western powder in several of my reloads I do see their pressure numbers. Scroll to page 48 for 5.56 pressure numbers.
http://www.accuratepowder.com/load-data/

kwg

The "k" is a multiplier, as in 1000x. Or, 58 kpsi = 58000 psi.

C.U.P. has nothing to do with any of this. CUP figures were the what the old copper crusher method would yield. The copper crusher method has been obsolete since about the 80s, I think. what I am talking about is a difference between the European methods and American method of pressure measurement.

Having run HOT N540 service rifle loads for years, to the tune of likely over 100K of them... the AR can handle more than most give it credit for by far...