5.56 m855 penetrator in a .223 rifle?


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slash415
March 9, 2012, 04:18 PM
I just bought a Savage Axis in .223. So far it has been
an awesome gun to shoot. Today I was at Acadmey Sports, they had a box of m855 penetrators for seven bucks. I was wondering if I could safetly fire these rounds from my Axis?

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GhostRanger
March 9, 2012, 04:27 PM
Not recommended. 5.56x45 rounds have a higher pressure than .223. You "can" shoot them but it puts excess stress on your rifle.

zxcvbob
March 9, 2012, 04:30 PM
Check with Savage. I have a new Ruger Mini-14 ranch rifle and it's stamped .223 Remington, but the manual and Ruger's web site say all but the target models are both .223 and 5.56.

I think the real difference between .223 and 5.56 is the 5.56 chambers are cut to allow longer bullets. The maximum pressures are about the same, just specified differently.

firesky101
March 9, 2012, 04:33 PM
There is another thread about this right now. If you really want to try it, go ahead, it PROBABLY wont damage the rifle. If you experience sticky extraction, or blown primers it is time to stop. The issue is the longer bullets causing overpressure due to engaging the rifling early. I personally would not do it, but your rifle not mine.

http://www.thehighroad.org/showthread.php?t=647716

Edit to add link to thread.

GRUMPA
March 9, 2012, 04:40 PM
I wouldn't want to use those UNLESS it's clearly stamped on the rifle itself. 5.56 ammo has a different leade in the chamber than a 223, and the pressures are greater in the 5.56 than a 223.

I have 2 different rifles that can shoot 223 but only one rifle that I can shoot 5.56 with.

NOLAEMT
March 9, 2012, 04:48 PM
the official rule is that no, you should not fire 5.56 in a .223 chamber, but from what I have heard, especially in a bolt gun, it is not really a concern.

coolluke01
March 9, 2012, 04:59 PM
I found this info helpful.

Much of the confusion in the pressure differences comes from the fact that NATO rounds are tested for pressure at the chamber mouth or barrel and the SAAMI tests it at the chamber.

.223 Remington versus 5.56 mm NATO



These 5.56x45mm NATO cartridges are identical in appearance to .223 Remington. They are, however, not completely interchangeable.
While the 5.56mm NATO and .223 Remington cartridges and chamberings are very similar, they are not identical.
While there is a myth that 5.56 NATO cases are thicker and hence have less capacity than commercial .223 cases, this has been shown to be false. Each brand of case and each manufacturing lot has a slightly different case capacity; 5.56 NATO and .223 commercial cases tend to have nearly identical case capacity when measured using the water test.[6] The NATO specification allows a higher chamber pressure. NATO EPVAT test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the location used by the United States civil standards organization SAAMI. The piezoelectric sensors or transducers NATO and SAAMI use to conduct the actual pressure measurements also differ. This difference in measurement method accounts for upwards of 137.9 megapascals (20,000 psi) difference in pressure measurements. This means the NATO EPVAT maximum service pressure of 430 megapascals (62,000 psi) for 5.56mm NATO, is reduced by SAAMI to 379.21 megapascals (55,000 psi) for .223 Remington.[7] In contrast to SAAMI, the other main civil standards organization C.I.P. defines the maximum service and proof test pressures of the .223 Remington cartridge equal to the 5.56mm NATO.
The 5.56mm NATO chambering, known as a NATO or mil-spec chamber, has a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 Remington chambering, known as SAAMI chamber, is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber (Bill Wylde)[8] or the ArmaLite chamber, which are designed to handle both 5.56mm NATO and .223 Remington equally well. The dimensions and leade of the .223 Remington minimum C.I.P. chamber also differ from the 5.56mm NATO chamber specification.
Using commercial .223 Remington cartridges in a 5.56mm NATO chambered rifle should work reliably, but generally will not be as accurate as when fired from a .223 Remington chambered gun due to the longer leade.[9] Using 5.56mm NATO mil-spec cartridges (such as the M855) in a .223 Remington chambered rifle can lead to excessive wear and stress on the rifle and even be unsafe, and the SAAMI recommends against the practice.[10][11] Some commercial rifles marked as ".223 Remington" are in fact suited for 5.56mm NATO, such as many commercial AR-15 variants and the Ruger Mini-14, but the manufacturer should always be consulted to verify that this is acceptable before attempting it, and signs of excessive pressure (such as flattening or gas staining of the primers) should be looked for in the initial testing with 5.56mm NATO ammunition.[12]

briantf
March 10, 2012, 04:30 PM
I've emptied out plenty of XM193 and M855 to get to the LC brass in a couple of Savage 223's. Neither 556 load takes advantage of the chamber difference. You better believe I inspect the brass, I reload it! There is zero indication of excess pressure.

At $3-4/box when I bought it that was an OK way to get good brass compared to virgin Winchester, not so much at $7/box. Sheesh, you'd think it would be coming down in price!

I've had factory Federal Fusion 270 WSM so hot I got extractor marks on the casehead, I'm more concerned about that kind of factory foul up than any theoretical "it's possible that....."

Maybe that Mk262 stuff loaded with 77gr SMK's takes advantage of the long lede, but until then, show me a 223 rifle blown up with M855. Then I might pay attention to all the hand wringers.

Regards,
Brian in CA

R.W.Dale
March 10, 2012, 04:38 PM
In a full sized bolt gun chambered for belted magnums I consider 223 and 5.56 to be the same.

Just because pressures spike beyond what saami would be worried about in a 223 does not mean they spike beyond what an action proofed for 270wby can handle.

posted via mobile device.

alsaqr
March 10, 2012, 05:43 PM
The claim that US military 5.56mm ammunition is loaded to a higher pressure than .223 ammunition is a popular SAAMI myth. US military 5.56mm ammunition, with the exception of the MK 262 round, is loaded to 52,000-55,000 psi.

See chapter 10, TM 43-0001-27:

http://ammo.ar15.com/ammo/project/hist_mk262.html

MK 262 ammo has the same overall lenght as the other 5.56mm ammo. Otherwise it would not fit the magazine.

http://ammo.ar15.com/ammo/project/hist_mk262.html

proven
March 10, 2012, 05:55 PM
Commercial SAAMI-specification .223 chambers have a much shorter throat or leade and less freebore than the military chamber. Shooting 5.56 Mil-Spec ammo in a SAAMI-specification chamber can increase pressure dramatically, up to an additional 15,000 psi or more.

you guys do what you want. this has been covered over and over again, and the general consensus is always to not use 5.56 in a .223 chambered rifle.

so you say you did and nothing happened? good for you. have you ever had a reciever kaboom next to your face? i haven't and am not going to do something to increase those chances, when both ammos are plentiful.

i had someone tell me that you could easily fire 5.45 russian in a 5.56....my response to him was the same....good for you, have fun with that.

helotaxi
March 10, 2012, 06:22 PM
I've heard from several reputable sources that the Savage rifles are not chambered to SAAMI spec specifically so 5.56 ammo doesn't cause pressure problems. Finding a rifle chambered to strict SAAMI spec is pretty challenging these days.

denton
March 10, 2012, 07:40 PM
One of my recent consulting gigs was working on an M855 issue at Lake City. That DOES NOT make me a general expert on the issue, but perhaps the following is useful:

The 5.56 does have a longer leade that the 223. However, you will not jam the bullet in the lands if you load M855 in a 223. That's because M855 has to fit in a standard M16 magazine. The M855 Lake City M855 ammo I have measures 2.250". I load longer than that for my bolt action 223.

The pressure standards for 5.56 and 223 are indeed different. They are also measured by different methods. Until we dig down through another layer of dirt, we can't say how the SAAMI spec compares with the NATO spec. SAAMI says 55,000 PSI MAP, and NATO says 62,350. But NATO does their measuring at the case mouth, and SAAMI measures in the middle of the case body. The strength of the brass usually creates about a 5,000 PSI difference, which MIGHT account for most of the difference.

Ramshot's reloading data includes a special section that goes to 62,350 PSI. I'll drop them a note and see if they can shed any light on the issue.

In my case, I don't care a lot... got a 5.56.

Ar180shooter
March 10, 2012, 09:16 PM
I've heard from several reputable sources that the Savage rifles are not chambered to SAAMI spec specifically so 5.56 ammo doesn't cause pressure problems. Finding a rifle chambered to strict SAAMI spec is pretty challenging these days.
And that's especially true of rifles with faster twist rates designed to accommodate long, heavy .224 bullets.

OP, try a few rounds and check the brass for pressure signs.

Jeff F
March 10, 2012, 09:18 PM
you guys do what you want. this has been covered over and over again, and the general consensus is always to not use 5.56 in a .223 chambered rifle.

so you say you did and nothing happened? good for you. have you ever had a reciever kaboom next to your face? i haven't and am not going to do something to increase those chances, when both ammos are plentiful.

i had someone tell me that you could easily fire 5.45 russian in a 5.56....my response to him was the same....good for you, have fun with that.

Can anyone show me one .223 rifle that has blown up from shooting 5.56 in it?

proven
March 10, 2012, 09:55 PM
http://winchesterle.com/resources/articles/Pages/223remvs556mm.aspx

some info from winchester, which loads both.

http://m4carbine.net/showthread.php?t=55149

as i said, do what you want.

R.W.Dale
March 10, 2012, 10:04 PM
http://winchesterle.com/resources/articles/Pages/223remvs556mm.aspx

some info from winchester, which loads both.

http://m4carbine.net/showthread.php?t=55149

as i said, do what you want.

From the second link

(The following is just a generalization to demonstrate the concept. DO NOT hold me to the exact numbers as they are not correct and they ignore the difference due to the different methods used to measure chamber pressure.)

What that says is the poster guessed and MADE UP a completely fictional pressure map.

again pressure can spike all it wants. short of a case full of reddot you're not going to cause a savage/ruger77/or rem700 ect the slightest distress with a piece of 223 brass.

17 rem shows us the .223 case head is good for 63K psi all day long.


Again cite one instance of m855 causing a ,223 bolt rifle any distress at all



posted via mobile device.

proven
March 10, 2012, 10:12 PM
ned christiansen's quote is what i would pay attention to.

alsaqr
March 10, 2012, 10:20 PM
as i said, do what you want.

i intend to just that, as i have been doing since 1968.

Show me the kaboom.


What that says is the poster guessed and MADE UP a completely fictional pressure map.

Bingo: Figures sometimes lie and liars often figure.

proven
March 10, 2012, 10:23 PM
i intend to just that, as i have been doing since 1968.


haha. cheers, buddy

denton
March 10, 2012, 11:34 PM
OP, try a few rounds and check the brass for pressure signs.

Ummmm.... no pressure signs means that you are operating under about 70 KPSI. Sure you want to use that as your guide?

helotaxi
March 11, 2012, 04:29 AM
If you look at the CIP standards for .223 (they are different than the SAAMI standards) they can be directly compared to 5.56 since they use the same pressure measuring method. They specify the same pressure for both, and using the same units (SAAMI pressure for the .223 is in CUP which can't be converted to PSI). The difference is in the leade and freebore of the rifle chamber. 5.56 ammo IS loaded hotter even though the max pressure specified and reached is the same. The longer freebore and shallower leade allow the hotter load to stay within the same pressure limit. Firing that hotter load in a spec .223 chamber with the shorter freebore and more abrupt leade can lead to proof load level pressures. This has been tested and confirmed.

zxcvbob
March 11, 2012, 10:34 AM
Helotaxi, that's the most concise and logical explanation I've ever seen. And it makes sense. Do you you have any references where we can verify this, or is it all from memory?

alsaqr
March 11, 2012, 10:50 AM
Since 1968 i have fired hundreds of thousands of military 5.56mm rounds
in the chambers of .223 rifles. There have never been any signs of high pressure.

SAAMI waited until millions of surplus 5.56mm rounds hit the market before making their earthshaking revelation.

The question here becomes: Would SAAMI lie to you. My answer is a resounding yes. SAAMI has lied before.

A few years ago SAAMI asked OSHA to revise and consolidate outdated rules for small arms ammunition manufacturing and storage. There was one big problem, SAAMI did this without first consulting the manufacturers.

OSHA drafted a publication and put it out for comment. For nearly 50 years i've been an EOD guy who has stored and used thousands of tons of explosives of all types, consulted with explosive and propellant manufacturers on problems, and written plans for ammunition storage now used by the military of two nations. To those of us familiar with ammunition manufacture and storage there was nothing earthshaking in the proposed publication.

The ammo makers had a fit and complained to SAAMI. SAAMI called the NRA and told them the sky was falling and the world as we know it was about to come to an abrupt end. SAAMI forgot to tell the NRA that they asked for the publication.

The NRA and NSSF, without first reading the proposed new publication, jumped all over OSHA for doing what SAAMI asked them to do. Gunowners got energized, imagined the world was ending and called their congress critters.

Yes, SAAMI would lie to you.

Link:

http://www.thehighroad.org/showthread.php?t=285452&page=4&highlight=proposed+new+ammunition+regulation

alsaqr
March 11, 2012, 10:51 AM
Show me the kaboom from using 5.56mm ammo in the .223 chamber of a gun in good condition. Anyone?

There is one .223 gun i'm familiar with that i would not shoot 5.56mm ammo in; matter of fact i got rid of mine and will never own another one. That is the single shot H@R Handi-Rifle. Some of those guns show pressure signs with commercial .223 ammunition. In 1994, while working close to the H@R plant in MA, i met an H@R gunsmith. i asked a him why their .223 chamber dimensions ranged from huge to extremely tight. It turns out that H@R were re-grinding their reamers.

Several of my .223 guns were made in Europe in the past 10 years. None of those Eurpoean gun makers warn of using 5.56 mm ammo in .223 chambers.

i am not recommending that anyone use military 5.56mm ammunition in a .223 chamber. If you don't feel comfortable doing it then don't.

helotaxi
March 11, 2012, 10:57 AM
Helotaxi, that's the most concise and logical explanation I've ever seen. And it makes sense. Do you you have any references where we can verify this, or is it all from memory?

EDIT: Unregard. Early in the morning and forgot the topic I was posting in.

It's from memory and distilled down from having to repeatedly answering the question. I don't put much faith in Wikipedia, but the cartridge and chamber prints are hard to dispute and they can be found there. Google will turn up the CIP standards as well as the NATO standards.

HoosierQ
March 11, 2012, 11:53 AM
Wheeeeee....these are always a fun ride :rolleyes:

Ar180shooter
March 11, 2012, 01:19 PM
Ummmm.... no pressure signs means that you are operating under about 70 KPSI. Sure you want to use that as your guide?
.223 and 5.56 operate at about the same pressure as the NATO maximum pressure of 62,000 PSI works out to be about the same as the SAAMI 52,000 CUP. The only appreciable difference between SAAMI and NATO chamber specs is the amount of freebore. This is what can potentially cause the pressure spike, using heavier bullets in NATO cartridges. It has nothing to do with NATO and SAAMI spec cartridges operating at different pressures, as they don't. Now, most manufacturers use modified SAAMI chambers, as the fast rate of twist, which allows for heavier, longer bullets to be used, necessitates an increase in the amount of freebore in the chambers. The Savage Axis has a 1 in 9 in twist rate, meaning it's designed to accommodate heavier bullets, up to about 68 grains (M855 contains 62gr projectiles). So theoretically, there should be no issues with firing M855 out of his rifle, but I was suggesting he try a few rounds to verify that there isn't an unsafe pressure spike before shooting large quantities of it through his rifle.

helotaxi
March 11, 2012, 04:08 PM
The only appreciable difference between SAAMI and NATO chamber specs is the amount of freebore. This is what can potentially cause the pressure spike, using heavier bullets in NATO cartridges. The leade angle is also different and probably the more important difference. Bullet weight has nothing to do with it either. The chambers were different even before the NATO load moved to the 62gn M855 bullet. Even M193 will cause high pressures in a .223 chamber and it is a 55gn bullet. The 5.56 has always been loaded hotter and has always needed the longer freebore and shallower leade to keep pressures within limits.

The presence of heavier bullets and faster twists have nothing to do with the reason that most rifles don't have a SAAMI spec chamber. Liability and the knowledge that people are going to fire 5.56 ammo in their .223 rifles is the reason. Bullets that can be stabilized in a 1:9 twist don't need anything special with regard to chamber accommodations. Pressures with such bullets would be controlled the same way you normally control pressure, with powder selection and load work-up.

zxcvbob
March 11, 2012, 04:59 PM
If I understand that, it has to do with the volume of the chamber; giving the gases a little more room to expand before the bullet accelerates down the bore and gets out of the way.

The War Wagon
March 11, 2012, 05:08 PM
PMC Bronze is your friend. Do NOT count on Chairborne Rangers footing your medical expenses, should you blow up your rifle, and parts of your anatomy with it. :eek:

denton
March 11, 2012, 05:57 PM
.223 and 5.56 operate at about the same pressure as the NATO maximum pressure of 62,000 PSI works out to be about the same as the SAAMI 52,000 CUP. The only appreciable difference between SAAMI and NATO chamber specs is the amount of freebore.

Absolutely not so.

5.56 operates at up to 62,350 PSI measured at the case mouth. 223 operates at 55,000 PSI measured in the middle of the case body. Yes, the 223 is also spec'd at 52,000 CUP. But that is not the source of the discrepancy. If you keep everything in PSI, there is just over 7,000 PSI difference in the pressure numbers, about 5,000 PSI of which MIGHT be from difference in the measurement system.

Ramshot did some testing on that, and I have a note in to them asking for more info. I may have something to post in a day or two.

Magnuumpwr
March 11, 2012, 10:55 PM
I have a Savage 112 FV, that best I can understand, I can change that caliber by changing the bolt head, barrel, and blind mag floor plate. So shooting M855 does not worry me, it's the same ammo I use in my AR's. I also have a Savage 12 BVSS, but I will do some research prior to firing the M855 from it.

awgrizzly
March 12, 2012, 12:21 AM
Common sense makes it hard to believe the stuff being reported about .223 & 5.56 ammo.

1) 5.56 with heavier bullets are longer and stick into the back of the rifling.
--- This just isn't so, both have a max overall length of 2.260 inches. The longer bullets have to be seated deeper, and a longer length bullet won't fit in the magazine.

2) The 5.56 has a higher pressure specification.
--- Hard to say since they are said to measure pressures differently, but I do believe this may be true, since I believe I read that the M855 has a muzzle velocity well over 3000 (must take a lot of pressure). However, the M16 chamber and the AR15 are the same except for the longer leade (refer to item 1 above) and the M16 fires full auto. If the M16s don't blow up the ARs should be OK.

3) Differences in .223 and 5.56 case sizes.
--- This has been thoroughly debunked here already.

4) That leaves me with one more point few raise. What might happen if a gun company, dealer, or other professional tells a person it's safe to shoot a 5.56 in a .223, then something goes wrong and he gets hurt? Court will certainly be the next step. So common sense tells me that professionals will never tell you to shoot a 5.56 in a .223.

coolluke01
March 12, 2012, 01:44 PM
Case dimensions are identical. I always though the angle of the shoulder was different though.

5.56
http://en.wikipedia.org/wiki/File:5.56x45mm_NATO.jpg

.223
http://en.wikipedia.org/wiki/File:.223_Remington.jpg

alsaqr
March 12, 2012, 02:45 PM
Let's see:

1. SAAMI says military 5.56mm cases are thicker (heavier) than commercial .223 cases. This is not true of US military 5.56mm cases. i've been weighing cases since 1968. the thickest US made cases are Federal American Eagle and Federal Gold Metal .223 cases. Brit military cases are thick. The thickest cases are Lapua. See tech, see brass weights.

http://ar15barrels.com/tech.shtml

SAAMI has published both CUP numbers And ANSI psi numbers for numerous cartridges but not the .223. Wonder why?

http://www.shootingsoftware.com/ftp/psicuparticle2.pdf

denton
March 12, 2012, 03:59 PM
http://saami.org/specifications_and_information/publications/download/206.pdf

Scroll down to page 19. It's there. 55,000 PSI MAP.

Ar180shooter
March 12, 2012, 09:50 PM
http://saami.org/specifications_and_information/publications/download/206.pdf

Scroll down to page 19. It's there. 55,000 PSI MAP.
Don't you find it odd that the .270 Win is specd for 52,000 ANSI CUP and 65,000 ANSI PSI, but .223 Rem is specd for 52,000 ANSI CUP and 55,000 ANSI PSI?

The implication is either one of those numbers is grossly inaccurate, or either the ANSI PSI or ANSI CUP system of pressure measurement is dangerously inaccurate.

Jeff F
March 12, 2012, 10:47 PM
Good catch there, something to ponder.

helotaxi
March 13, 2012, 12:08 AM
Absolutely not so.

5.56 operates at up to 62,350 PSI measured at the case mouth. 223 operates at 55,000 PSI measured in the middle of the case body. Yes, the 223 is also spec'd at 52,000 CUP. But that is not the source of the discrepancy. If you keep everything in PSI, there is just over 7,000 PSI difference in the pressure numbers, about 5,000 PSI of which MIGHT be from difference in the measurement system.

Ramshot did some testing on that, and I have a note in to them asking for more info. I may have something to post in a day or two.
Look at the CIP standards which use the same measuring method as NATO. They specify the exact same pressure for the .223 and the 5.56. Again the difference is that the chamber of the 5.56 allows a cartridge with more powder behind the bullet to stay within that pressure limit. That is the only point that really matters in the discussion. The case dimensions are the same. The cases are the same. The bullets are the same. The rifle can handle the pressure of the 5.56 round, because if the rifle is produced or sold in Europe, that is the pressure of commercial loaded ammo in the proper chamber. The problem is that 5.56 ammo in the .223 chamber generates MORE pressure than the 5.56 round does in a 5.56 chamber. Tested into the 85kpsi range kind of more. That's proof load territory.

CUP is a terrible pressure measurement tool. It was used when developing load data because it was all that was available at the time. Now that piezo transducers are available that can provide real time pressures in fractions of a millisecond intervals, it is the new standard. CUP does not translate to another unit of measure.

The standards linked on the SAAMI web page is dated from 1992. There are at least 2 more recent versions of the .223 standards in particular that supersede that data. It would be nice if SAAMI would update their resources.

denton
March 13, 2012, 12:14 AM
Look at the CIP standards which use the same measuring method as NATO.

No they don't.

CUP is a terrible pressure measurement tool.

I wouldn't say terrible, but I would say far short of ideal.

CUP does not translate to another unit of measure.

Yes it does. Article from Varmint Hunter (http://www.shootingsoftware.com/ftp/psicuparticle2.pdf)

denton
March 13, 2012, 12:25 AM
Don't you find it odd that the .270 Win is specd for 52,000 ANSI CUP and 65,000 ANSI PSI, but .223 Rem is specd for 52,000 ANSI CUP and 55,000 ANSI PSI?

Yes I do. If you take graph paper, put CUP on the horizontal axis and PSI on the vertical axis, then put a dot on the chart for all the SAAMI cartridges that have specs for both, the 223 is a statistical outlier on the trend line. I have no idea why that happened, but something apparently changed between the time they set the CUP spec and the time they set the piezo spec.

helotaxi
March 13, 2012, 12:32 AM
No they don't.I stand corrected but the fact remains that the pressure number is the same. Pressure should be the same throughout the vessel and peak pressure occurs after the bullet has left the case. Whether the transducer is in the neck or body of the case is splitting hairs.

I wouldn't say terrible, but I would say far short of ideal.For what it is meant to measure, it's truly terrible. When it was all that there was, it was better than nothing, but not by much. Now that there are methods for measuring pressures directly, all references to CUP need to be eliminated. I can get about as accurate a measurement of length by looking at something as a copper crusher gives of peak pressure...actually I can probably eyeball it better. I wouldn't trust my TLAR with my safety.

denton
March 13, 2012, 12:47 AM
Now that there are methods for measuring pressures directly, all references to CUP need to be eliminated.

On that, we are in violent agreement. It won't be long before CUP is just a quaint historical footnote, which is where it belongs.

Whether the measurement is taken at the center of the case or at the mouth is definitely not splitting hairs. Having the brass case between the gas and the chamber produces an offset in the neighborhood of 5,000 PSI. I know Ramshot did some testing on that, and found an offset closer to 1,000 PSI. I'm trying to get some additional information from them. Maybe it is a big deal, maybe not.

If all else fails, I have a dual trace pressure measuring system that I built. If I get to be curious enough, I do have the ability to take two simultaneous measurements, one at mid-case and one at the case mouth, on the same cartridge. But I'd much rather mooch data from someone who has already done that.

Ar180shooter
March 13, 2012, 10:07 AM
Yes I do. If you take graph paper, put CUP on the horizontal axis and PSI on the vertical axis, then put a dot on the chart for all the SAAMI cartridges that have specs for both, the 223 is a statistical outlier on the trend line. I have no idea why that happened, but something apparently changed between the time they set the CUP spec and the time they set the piezo spec.
So why is this?

If the CUP method was that inaccurate, don't you think we would have seen quite a number of rifles blown up as a result?

As the .223 is the statistical anomaly, and the C.I.P. lists .223 and 5.56 as operating within the same pressure specifications, I'm inclined to discount the SAAMI numbers as inaccurate. Plus, maybe being in Canada leads me to favour C.I.P. over SAAMI anyway.

denton
March 13, 2012, 12:30 PM
At the same time that I did the conversion formula from CUP to PSI, I did another one for converting back and forth between CIP and SAAMI PSI. But that was two computers ago. Last night, I looked for the spreadsheet and didn't find it. I'll check my relic out in the workshop and see if it is hiding there.

CIP and SAAMI PSI are pretty highly correlated, but you cannot simply substitute one number for the other, any more than you can substitute CUP for PSI.

So why is this?

I think it is because humans were involved.

Edited to add:

Found the CIP SAAMI conversion formula: SAAMI PSI = -17040 + 1.269 * CIP PSI.

Plugging the CIP spec of 62,366 into the formula predicts a SAAMI spec of 62,102. So no great difference from system to system for that cartridge. That lends credibility to the argument that the SAAMI 223 PSI spec is artificially low.

Still looking for some info from Ramshot.

Coltdriver
March 13, 2012, 07:48 PM
I have both calibers. I have shot hundreds of of 5.56 rounds from .223's. But there is one thing you really should pay attention to.

That is the chamber on your .223. I have found the ogive on most 5.56 ammo to have a shorter radius making the fat part of the bullet stick a bit further into the chamber.

If you have a tight .223 chamber you may very well engage the lands in your .223 with the 5.56 bullet. This will cause excessive pressure.

I have never, ever, heard of a .223 blowing up from shooting 5.56. Your mileage may vary. But it is just not prudent to stuff a bullet into the rifling.

I always measure the chamber or just chamber a round. If the bolt closes hard it is very hard on your lugs and you can gall them easier than you might imagine. It also means you probably stuffed the bullet into the lands. You should know with certainty what your situation is.

I have a tool that makes it easy for me to measure the bullet combination I intend to use. With the tool I can tell in about two minutes if its ok or not.

My Ruger .223 has a chamber that is too tight for 5.56 so I don't shoot it in my Ruger. But I have had several other .223's including some Thompson Center Contender and Encore barrels that 5.56 worked in just fine.

denton
March 13, 2012, 08:00 PM
Here is the reply I got from Ramshot. It does help some.

You are correct; the tests methods for SAAMI and NATO are different. All of our published loads were tested using the SAAMI Conformal method with a Transducer measuring chamber pressure in a 223 barrel. The 5.56 chamber provides for lower pressures, because of the free bore length and the lead angle. We have performed numerous tests comparing Case Mouth pressures with Chamber Pressures, and at 62350 psi Chamber pressure, you will have a safe port mouth pressure in your 5.56.

OK... all testing done in a 223 chamber. All testing was done with the SAAMI test method, none with the NATO test method. Their 62,350 PSI 223 load will produce lower pressure in a 5.56 chamber. They have checked case mouth vs. mid-case measurements against each other, and are satisfied that their 62,350 PSI loads are safe in a 5.56.

That's helpful.

alsaqr
March 13, 2012, 08:49 PM
The US Army has acceptance standards for ammunition and everything else. Every lot of military ammunition is tested, accepted or rejected by civilian Quality Assurance Specialsits Ammunition Surveillance (QUASAS).


My only copy of the acceptance standards for 5.56mm ball ammo is out of date. MIL-C-63989C dated 15 February, 1994:

3.6 Velocity. The average velocity of the cartridges,
conditioned at 700 + 2F, shall be 3000 feet per second (fps) plus
or minus 40 fps at 78 feet from the muzzle of the weapon. The
standard deviation of the velocities shall not exceed 40 fps.

3.7 Chamber pressure. The average chamber pressure of the
sample cartridges, conditioned at 70 + 2F shall not exceed
55,000 psi. Neither the chamber pressure of an individual sample
test cartridge nor the average chamber pressure plus three standard
deviations of chamber pressure shall exceed 61,000 psi.

The War Wagon
March 13, 2012, 09:23 PM
And the WINNER is...

http://www.m4carbine.net/showthread.php?t=55149


ta da. :D

R.W.Dale
March 13, 2012, 09:52 PM
And the WINNER is...

http://www.m4carbine.net/showthread.php?t=55149


ta da. :D

You do realize that was posted to this thread several days ago right? :rolleyes:

posted via mobile device.

alsaqr
March 13, 2012, 10:06 PM
Never hear of a .223 rifle having a kaboom with 5.56 ammunition. Cant' say the same about using .223 ammo in .223 chambers. Winchester Ranger law enforcement ammo destroyed four SWAT AR-15 rifles during a training session. Looks like Winchester does not test every lot.


http://www.thetruthaboutguns.com/2011/03/robert-farago/winchester-ranger-223-ammo-recall-explained-almost/

Attention Law Enforcement Agencies, this Police Department is seeking any similar incidences with the .223/5.56 style rifles.

On 02/14/11 an officer was attending an M4/MP-5 class and during a shooting session, the .223 rifle (Stag Arms) experienced a catastrophic failure resulting in an upper receiver cracking and the bolt being pushed into the bolt assembley.

During a SWAT training day on 02/23/11, three more M4 style rifles experienced a catastrophic failure at the same time. All three rifles experienced the bolts being pushed into the bolt assembly, the upper receivers were cracked and / or broken apart, and the lower receivers were bowed outward. The ammunition we used in all the rifles were Winchester RA223R2 Ranger 64 gr. Power Point.

The Rifles were: 1-Colt, 2- Bushmasters and 1 – Stag Arms


OFFICIAL RECALL NOTICE

East Alton, IL – Olin Corporation, through its Winchester Division, is recalling six (6) lots of its RANGER 223 Remington 64 Grain Power-Point (PP) centerfire rifle ammunition (Symbol Number RA223R2). Through extensive evaluation Winchester has determined the lots of RANGER Law Enforcement ammunition listed below may contain incorrect propellant. Incorrect propellant in this ammunition may cause firearm damage, rendering the firearm inoperable, and subject the shooter or bystanders to a risk of serious personal injury when fired. To determine if your ammunition is subject to this notice, review the Lot Number . . .

If the last four characters of the Lot Number are DK01, DK11, DK21, DK31, DK41 or DK51 immediately discontinue use and contact Winchester toll-free at 866-423-5224 to arrange for replacement ammunition and free UPS pick-up of the recalled ammunition.

The War Wagon
March 13, 2012, 10:34 PM
You do realize that was posted to this thread several days ago right? :rolleyes:

Awesomeness bears repeating... ;)

alsaqr
March 13, 2012, 10:45 PM
i like this quote from The War Wagons link:


(The following is just a generalization to demonstrate the concept. DO NOT hold me to the exact numbers as they are not correct and they ignore the difference due to the different methods used to measure chamber pressure.)

awgrizzly
March 14, 2012, 01:29 AM
I have both calibers. I have shot hundreds of of 5.56 rounds from .223's. But there is one thing you really should pay attention to.

That is the chamber on your .223. I have found the ogive on most 5.56 ammo to have a shorter radius making the fat part of the bullet stick a bit further into the chamber.

If you have a tight .223 chamber you may very well engage the lands in your .223 with the 5.56 bullet. This will cause excessive pressure.

Thank you Coltdriver, I suspected as such but I never heard it stated by another. The thing I wrestled with was that the cartridge dimensions are the same, and the heavier bullets could not make the overall length longer and still be in spec (or even fit in the magazine). But it still puzzled me because the same chubby bullets would be loaded in .223 cartridges as well as the 5.56 NATO.

Then I read the link provided by The War Wagon and it all fell together. Basically, the difference in leades produces lower pressure in the 5.56 NATO chamber and as a result the military is able to spec higher pressure loads.

sniper762
March 14, 2012, 04:39 PM
I've shot 1000s of 5.56 in my savage .223 rifle......no problems

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