223 CIP rating- Safe to Shoot 5.56 - CZ USA says so

[pnorris]

I have been looking for a bolt rifle which can safely shoot 223 and 5.56. When I approached Tikka I was point blank told only to shoot 223. Yet, on their website they say that they meet the CIP standard. Now, I just perused CZ's website and found this information:

Q: “Can CZ rifles chambered in .223 fire 5.56 ammunition safely?”
A: All of our .223s will happily eat 5.56. Since our factory is in Europe, we build everything to CIP spec, which doesn’t differentiate between the two cartridges and just has the higher pressure as its standard. So the CZ .223s will shoot everything from the cheapest Russian steel to match .223 brass ammo.

As such, why would Tikka say only 223, yet CZ says fire away since we meet CIP. Obviously, this would make available choices much better, as I believe most of the European brands meet CIP. Any thoughts?

 

[spife7980]

Because two different things are two different things.

 

[Newbie2020]

I wish they’d all have done that about 4 decades ago! Geez!

 

[pnorris]

Because two different things are two different things.

I don't think you are getting what I am saying. Both Tika and CZ appear to follow the CIP standard. CZ says go ahead and use 5.56, because under the CIP standard it is safe. Yet, Tikka says don't use 5.56. My understanding is that the CIP standard accounts for the increased potential pressure of 5.56. As such, I am trying to understand why. I believe Bergara is the same.

 

[spife7980]

I don't think you are getting what I am saying. Both Tika and CZ appear to follow the CIP standard. CZ says go ahead and use 5.56, because under the CIP standard it is safe. Yet, Tikka says don't use 5.56. My understanding is that the CIP standard accounts for the increased potential pressure of 5.56. As such, I am trying to understand why. I believe Bergara is the same.

No, I get exactly what you are saying. But as to why two different entities take two different approaches there is no answer that can be supplied here as we are not those two entities. You are looking for something that doesnt exist here on a public internet forum.

You want the best answer? Because they have two different lawyers.

 

[pnorris]

OK, I understand what you are saying now. I guess the general question is whether it is safe to assume if a rifle meets CIP standards for 223 that it is safe to shoot 5.56. Am I wrong to make that assumption, or is my assumption a safe one, with the emphasis on safe.

 

[mcfred]

Why? Liability and litigious Americans.

"Modern" bolt guns will hold a lot of pressure. CZ has published 3550 bar pressure limit on their 527 actions with a 7.62x39mm (Ø.447") bolt face. That's nearly 8,100 lbs of bolt thrust. A Ø.375 case head 5.56x45mm NATO round at a high 70,000psi is only 7730 lbs of bolt thrust.

Bolt guns will hold the pressure and Czech people have faith that their product won't take your face off. Trust the product and not the lawyers.

(look above the mag)

 

[pnorris]

Great info, however, back to the original question. If the rifle is spec'd to CIP for 223 can we assume it can safely shoot 5.56, or am I taking a risk?

 

[mcfred]

If you're concerned and you require the internet to assuage your concerns then perhaps you should just opt out.

 

[Ledzep]

"Safe" by what definition?

Will your gun blow up and shrapnel you? No.
Will you potentially pop a primer? maybe.. probably not.
Will you exceed .223 SAAMI pressures? probably.

Many bullets designed for 5.56 have a larger bearing surface in front of the case mouth or cannelure that definitely conflicts with .223 freebore length. In other words, in my CZ 527 .223 MTR when I chamber Hornady 75gr BTHP 5.56 NATO (the one with the stumpy T2 ogive, not the typical 75gr bthp with the longer sleeker ogive), I jam it in the lands by .035" or so. Most assuredly that increases chamber pressure (jam vs. jump). To an unsafe level? I don't think so. It's probably over SAAMI MAP but so are probably the vast majority of people's hand loads that are at max published load up to 3-4 grains over max...

ETA: Never popped a primer, never flattened a primer, never an ejector slot mark... but what most people don't realize is that when you start seeing that stuff you're probably well north of 70ksi.

 

[pnorris]

"Safe" by what definition?

Will your gun blow up and shrapnel you? No.
Will you potentially pop a primer? maybe.. probably not.
Will you exceed .223 SAAMI pressures? probably.

Many bullets designed for 5.56 have a larger bearing surface in front of the case mouth or cannelure that definitely conflicts with .223 freebore length. In other words, in my CZ 527 .223 MTR when I chamber Hornady 75gr BTHP 5.56 NATO (the one with the stumpy T2 ogive, not the typical 75gr bthp with the longer sleeker ogive), I jam it in the lands by .035" or so. Most assuredly that increases chamber pressure (jam vs. jump). To an unsafe level? I don't think so. It's probably over SAAMI MAP but so are probably the vast majority of people's hand loads that are at max published load up to 3-4 grains over max...

ETA: Never popped a primer, never flattened a primer, never an ejector slot mark... but what most people don't realize is that when you start seeing that stuff you're probably well north of 70ksi.

By the way, how do you like the 527 MTR. I am considering that rifle. Yeah, I thought that CIP were higher pressures than SAAMI, and thus, if the 223 met CIP you would be good to go shooting 5.56. I want a bolt that can run both, as I have a large stash of 77 grain OTM that runs great in my ARs and is very accurate.

 

[pnorris]

If you're concerned and you require the internet to assuage your concerns then perhaps you should just opt out.

I thought this was a discussion forum . . . . . . . . .

 

[mcfred]

What's the discussion? The manufacturer says it's fine. Are they not *THE* experts about their product? Is there really still room for discussion regarding safety?

 

[aljones_315]

everytime you pull the trigger your taking a risk. regardless of what anyone tells you. thats with any ammo period whether you want to take it up a notch and shoot 5.56 is totally up to you but if the manufacturer says no id probably go with no. have i shot 5.56 out of a 223 yes have i had issues? no i havent but thats a choice i made you have to decide if your willimg to risk it.

 

[fdkay]

Buy the CZ and have no worries. Done.
If you REALLY want the Tikka, have a smith run a Wylde chamber reamer in it. Should only take a few minutes.

 

[natdscott]

It’s all about chamber dimensions.

5.56x45 Mk262 ammo, fired in a zero freebore varmint .223 chamber, is gonna go pretty poorly.

 

[shoot4fun]

The problem I have with your question is not really about 5.56/223 interchangeability as it is about pressure interchangeability. Just how does CIP correlate to pressures established by SAAMI when we get data of which some is designated in CUP and some in PSI?
Besides the CIP and SAAMI specs NATO seems to have its own specs.
Here are some data points that are interesting: (please verify them yourself as I am NO expert)
CIP
556 Nato max pressure 62,000 PSI
223 Remington max pressure 62,000 PSI

SAAMI
556 NATO 55,000 PSI
223 Remington 55,000 PSI
****556 NATO chamber throat is .125" longer than 223****

SO, apparently (in my mind) it would depend on if your 556NATO ammo stash is loaded to CIP or SAAMI pressure and just which chamber reamer was used to chamber the barrel. Does your ammo show that it is loaded to CIP or SAAMI specs somewhere on the box?
The Wylde chamber was, IIRC, to allow either.
Check out his link:

What is 223 Wylde? How Does it Compare to 5.56?

It's growing quickly in some shooting circles but what is 223 Wylde and why should you consider a rifle chambered in it instead of 5.56 or .223 Remington?

www.ammunitiontogo.com

 

[pnorris]

I have been looking for 223 Wylde chambered rifles, however, outside of custom rifles there are very few which is frustrating. I don't understand why manufacturers just don't start chambering for 223 wylde. I really like the mk262 round, as it shoots amazingly well in my knight's rifles and would love to use the same ammo in a bolt gun. What created this discussion was the info on CZ USA's website which seems to say . . . if it meets 223 CIP, 5.56 Nato ammo is safe as well. That was contrary to what other manufacturers said about their rifles. As such, I was curious whether the other manufacturers, such as Tikka, were just being overly cautious, or is there a reason which makes it potentially more risky in their rifles.

 

[whatsupdoc]

223 REMINGTON AND THE 5.56X45mm MILITARY/NATO CARTRIDGE AND CHAMBERS « Western Powders

5.56x45mm vs. the .223 Remington Pressure Specifications and Ratings
The problem with comparing the pressure rating of these two cartridges is that the three standards organizations utilize different methods of measuring pressure. The NATO EPVAT measures chamber pressure in Mega Pascals (MPa) at the case mouth, which results in higher peak pressures, as opposed to the location used by the United States civil standards organization–(SAAMI), which measures cartridge pressure in PSI at .025” behind the shoulder outside the case with a conformal sensor. The CIP European organization measures the pressure in bars (atmospheres) via a hole drilled in the case at 25mm forward of the case head. The piezoelectric transducers used to measure the pressure also are different. The NATO maximum service pressure is 430 MPa (62,366 psi) for the 5.56 mm NATO cartridge. The SAAMI rating is 55,000 psi for .223 Remington. In contrast to SAAMI, the European C.I.P. organization defines the maximum service pressure of the .223 Remington cartridges equal to the 5.56mm NATO chambering.


Several individuals have undertaken experiments with their own standardized recording method to compare the .223 Remington and 5.56x45mm. One such study was carried out detail by Andrew Tuohy. Tuohy evaluated various .223 and 5.56 ammo fired through rifles chambered for .223 Remington and 5.56x45mm. His research combined with the research of others including Barnes Bullets, generally confirms that shooting .223 ammo through a 5.56mm chamber results in lower pressure, but still functions (safely). Firing the same 5.56mm cartridge through a .223 chamber resulted in somewhat higher pressures– (~5%). Some commercial rifles marked as “.223 Remington” are also suited for 5.56 mm NATO, such as commercial AR-15 variants and the Ruger Mini-14

 

[natdscott]

Wylde is fine.

It’s far from the only game in town, however.

If I were setting up a barrel for magazine-length 5.56.... such as Mk 262...

...it would not be a Wylde.

 

[pnorris]

Wylde is fine.

It’s far from the only game in town, however.

If I were setting up a barrel for magazine-length 5.56.... such as Mk 262...

...it would not be a Wylde.

What would you use. I am always happy to learn.

 

[Ledzep]

By the way, how do you like the 527 MTR. I am considering that rifle. Yeah, I thought that CIP were higher pressures than SAAMI, and thus, if the 223 met CIP you would be good to go shooting 5.56. I want a bolt that can run both, as I have a large stash of 77 grain OTM that runs great in my ARs and is very accurate.

I like it. Doesn't quite shoot as good as a Bartlein, but easily good enough to kill plenty of prairiedogs and/or coyotes. The stock is comfortable and everything has worked out well so far. Only gripe is the twist rate. The newer ones have much better machining/finish on the metal parts, too. Looks like they changed over from having someone belt sanding to a CNC process with good surface finish.

 

[DownhillFromHere]

The simple answer to "why" was addressed above: *%^#@! lawyers and people who hire them to extort money from manufacturers.

My megabucks skeet gun is clearly stamped "USE FACTORY LOADED TARGET AMMUNITION ONLY" on the top barrel. O dearie me, I've probably run a hundred thousand reloads, not a few of which were heavy 20-gauge field loads used in 12-guage events, through it and somehow it's held together.

So here's a question... if I load a 77-grain Sierra Match King bullet to 2.26" OAL in a .223 Remington-headstamped case and that bullet emerges from my Tikka T3X Varmint at the same velocity as a MK262 5.56 round, with absolutely zero pressure signs, is it still .223 Remington? I hope so, because I've sure been doing it a long time. Of course, I would never run real MK262 ammo, though...

 

[Praeger]

Shoot your 5.56 and look for pressure signs. If there aren't any, carry on. If there is, stop.

 

[natdscott]

The simple answer to "why" was addressed above: *%^#@! lawyers and people who hire them to extort money from manufacturers.

My megabucks skeet gun is clearly stamped "USE FACTORY LOADED TARGET AMMUNITION ONLY" on the top barrel. O dearie me, I've probably run a hundred thousand reloads, not a few of which were heavy 20-gauge field loads used in 12-guage events, through it and somehow it's held together.

So here's a question... if I load a 77-grain Sierra Match King bullet to 2.26" OAL in a .223 Remington-headstamped case and that bullet emerges from my Tikka T3X Varmint at the same velocity as a MK262 5.56 round, with absolutely zero pressure signs, is it still .223 Remington? I hope so, because I've sure been doing it a long time. Of course, I would never run real MK262 ammo, though...

Nah, you’re wrong there. There are REAL differences in .223/5.56x45 NATO chambers.

Are they enough to blow a barrel with ammo set up for one vs the other? At the extreme ends.... “maybe”.

“Maybe” is enough to give any manufacturer—even a small one with a hometown lawyer—serious heartburn.

Freebore diameter and length has EVERYthing to do with the discussion.

 

[natdscott]

What would you use. I am always happy to learn.

Something shorter.

Bill built his chamber to be able to use magazine ammo, while also hybridizing it to work at 600 yards. Spec was to put the Sierra 80–at that time one of the only extant “Long” range .22 bullets—touching the lands at 2.475” COAL. It did that then, and a true virgin Wylde will do it now. If it is anything else, it’s not Bill’s chamber.

But the compromises made in Freebore to get better performance with single-fed rounds in a 600 yard AR.... well, the 77SMK from 2.255” just doesn’t really NEED that long a chamber.

While it’s true that more jump is not always bad, it is generally pretty damned accepted that you can’t put metal back IN the chamber. You CAN seat a 77 just a tech shorter if you want a little more jump.

Look to the Compass Lake reamer, or even a JGS NATO chamber, if ALL you wanna do is shoot magazine ammo.

 

[DownhillFromHere]

Nah, you’re wrong there. There are REAL differences in .223/5.56x45 NATO chambers.

Are they enough to blow a barrel with ammo set up for one vs the other? At the extreme ends.... “maybe”.

“Maybe” is enough to give any manufacturer—even a small one with a hometown lawyer—serious heartburn.

Freebore diameter and length has EVERYthing to do with the discussion.

There is no disagreement over differences in SAAMI specs between the two. There is, however, a legitimate comparison between CIT and SAAMI .223 spec. Based on CIT spec and actual observation, I am very confident that I am not overpressuring my handloads in my CIT-spec .223 Tikka even though I'm in MK262 velocity range. And I think that was what the OP was asking about. I'm not going to tell him or anyone else what is safe or not safe in their firearm, but I will report my own personal experience and rationale behind it.

 

[CaptNemo]

I’ve shot a little bit of M855 spec 5.56 through my Tikka and have pressure signs - ejector marks and mildly cratering primers. I’d use this ammo in a SHTF situation, but not a steady diet.
I wanted to run a few hundred rounds of this ammo thru the rifle to have brass to reload, but I don’t want to reload that brass. I ponied up and bought 300 pieces of Lapua brass for this rifle and will load this brass up for load development and shooting.

 

[Anb618]

It seems your concerns have been pretty well handled by others, so I’ll just say buy the .223 CZ. You won’t regret it. Mine’s a Varmint Kevlar (came from factory with HS Precision stock and 1:9 twist semi-heavy barrel). 69gr SMK handloads are a typical 3/4MOA, with occasional 1/2MOA if I can keep my own shit together. I haven’t been able to get to the range to run chrono on a seating depth test, but a new 50gr VMAX coyote load is showing some promise.