Okay guys tell me what yall think, last weekend I was breaking in my new American Spirit Arms M4...the weekend before I had taken it back to them because the barrel was overtightened and the front post was crooked as can be.
Any who, I was shooing Remington UMC at first and it had a few jams, thought it might have been the ammo.  I switched over to some Malaysian Millitary ammo and it worked fine.  Then...I started useing Winchester Ammo.  First shot jam, seconfshot jam, third shot KABOOM!!!
dropped the mag it was smokin' so I threw it, luckily it did not go off, but there was a very strange sight inside my half opened chamber, the shell was bent every direction below the chamber, with the bullet still there and one heckuvalotta unburned powder all over.  I left it like this and took it back to ASA this afternoon.
Now, quite a lot of the spent shells had marks from the extractor on them and I showed them some.  I left the rifle in its blown up condition and they blamed the whole thing on Winchester Ammunition.
I told them they probably didnt readjust the headspace  last week, they changed the subject.  Then they test-fired a bunch of PMC ammo and it worked fine and they said their rifles have a tighter something or other for accuracy (hokd) but they were going to take it in for a week and have their gunsmith look at all of the parts and check everything.

This rifle hasn't really done any good yet.  My Olympic Arms has only jammed on me once, useing any ammuniton.

I really thing I'm somehow being screwedhere...y

I can tell you right off what the problem is.....you were firing mil-spec 5.56mm through a .223 chamber. No, .223 and 5.56mm aren't the same thing! The 5.56mm is loaded much hotter and when fired in a chamber not designed to handle such loads, it can cause overpressures which can lead to things such as bent parts, damaged cartridge cases, failures to extract, and from time to time, KB's.

Only a few AR type rifles have a 5.56 compatible chamber, most notably Colt and Bushmaster...and perhaps some stuff from Rock River Arms and DPMS. But the vast majority of the rifles, especially kit guns, have the .223 chamber. For a rifle with a .223 chamber you are far better off to use .223 ammo, unless of course you want the problems you just listed to happen.

Next time, buy yourself some American Eagle 55 gr stuff made by Federal. It is good ammo and will work well in your gun. Reserve the mil spec stuff for mil spec barrels. And be sure to properly break your gun in. The UMC may have worked fine after some time. But keep in mind that ASA upper receivers aren't made from the best quality parts. ASA lowers are fine, but for upper's, choose something that uses chrome plated parts and chamber. Hope this was helpful. They need to start putting warning labels on this ammo, but oh well, I guess they think that the "only use in guns chambered for 5.56mm ammo" will suffice. The Malaysian probably wasn't packaged with any warning though. Be careful folks.

Quoted: I can tell you right off what the problem is.....you were firing mil-spec 5.56mm through a .223 chamber. No, .223 and 5.56mm aren't the same thing! The 5.56mm is loaded much hotter and when fired in a chamber not designed to handle such loads, it can cause overpressures which can lead to things such as bent parts, damaged cartridge cases, failures to extract, and from time to time, KB's. Only a few AR type rifles have a 5.56 compatible chamber, most notably Colt and Bushmaster...and perhaps some stuff from Rock River Arms and DPMS. But the vast majority of the rifles, especially kit guns, have the .223 chamber. For a rifle with a .223 chamber you are far better off to use .223 ammo, unless of course you want the problems you just listed to happen.

Yep, it's Colt, Bushmaster, DPMS, and RRA with 5.56NATO chambers on their AR-15 clones.  Others use a .223 chamber, and it's very important to make sure what you have.  Using 5.56NATO in a gun chambered for .223 is dangerous, while using .223 in a gun chambered in 5.56NATO is pretty safe.  The problem is most people automatically transpose the two as if they are equal, and they are not.

DJSSniper, you're not being screwed.  Just be thankful you're not seriously hurt by te KB.  And be careful with your Oly.  Oly's are chambered for .223, and using 5.56NATO in it could cause similar or worse problems.

For those of you out there with frankenguns or the like, it is equally important to verify what your rifle is really chambered for.  Some people sell rifles they built themselves with a certain company's lower, another company's upper, and another company's barrel.

Remember the Alamo, and God Bless Texas...

Quoted: Yep, it's Colt, Bushmaster, DPMS, and RRA with 5.56NATO chambers on their AR-15 clones.

I thought RRA use Wylde chambers, not 5.56 NATO.  Was I misinformed? Or do they offer a choice?

Quoted: Quoted: Yep, it's Colt, Bushmaster, DPMS, and RRA with 5.56NATO chambers on their AR-15 clones. I thought RRA use Wylde chambers, not 5.56 NATO.  Was I misinformed? Or do they offer a choice?

RRA has Wylde, 5.56 Nato and .223 chambers available, depending on the use/configuration of the rifle.

Not completely sure what happened to you, but Winchester ammo is complete shit.  Had some of their super-great Winchester hunting round for 300 Win Mag.  Did an eccentricity test on a couple of boxes and man was that shit ever off.  Some as much as 18mm.  Winchester is shit.  Put it in the same group as most of the Wolf ammo.

Also, starting sometime in 2001, Olympic has joined the 5.56mm group. I can't remember the exact date which they started using these chambers, but new Olympics do have them. I think Armalite also just recently (was it 2000?) started using the 5.56 chamber as well.

Quoted: Also, starting sometime in 2001, Olympic has joined the 5.56mm group. I can't remember the exact date which they started using these chambers, but new Olympics do have them. I think Armalite also just recently (was it 2000?) started using the 5.56 chamber as well.

Armalite's website lists the M15A4(T), M15A4(T) Carbine, M15A4, M15A4 Carbine, M15A2, M15A2 Carbin, and M15A2 National Match as all having .223 chambers.  They list no rifle chambered in 5.56NATO.  This may be an oversight on their part.

Olympic states their rifles are chambered to the minimum SAAMI specs.  That would rule out being chambered for 5.56NATO, as .223 REM is a SAAMI spec and 5.56NATO is a NATO spec.  They also specifically list not to use any Winchester ammo except for their target stuff, which is .223 REM.  Furthermore, they say not to use imported ammo, even imported ammo that is sold under the labels of US manufacture (IMI imported ammo sold as Winchester, etc.).

Yet, looking at their barrel info, they say their barrels are chambered for .223 REM, and are marked 5.56.  So, here's hoping they mean 5.56NATO, and would explain why the ammo hadn't caused a problem in his Oly.  I just wish they would not confuse the fact that .223 REM and 5.56NATO are NOT the same.

Remember the Alamo, and God Bless Texas...

Shouldn't the non Nato chamber brand guns have something to the effect of of dont use 5.56 nato too keep people like me from blowing myself up?
ASA never said a thing about it, but I am going to ask them when I get my rifle back.
And about my Oly, is it safe to use 5.56 or not...?...my reciever says "Cal. .223 5.56"
Talk about confusing, if I knew all this was gonna happen I wouldn't have gotten the ASA...

J&T Distributing states their uppers are chambered/reamed for 5.56 ammunition as well,at least that is what they told me when I asked.

So far I've had no problems with any ammunition I'ved used, which has included UMC,Lake City,Winchester, PMC,and Malaysian.

There's alot on the net dealing with the .223 SAAMI (sp?) vs 5.56 NATO question... I believe one of the FAQs this board references discusses it...

As for how to know, just ask the manufacturer. As I'm looking at kit guns, I've asked 'Which chamber do you use, SAAMI or NATO' The only kit company I've heard back from is JT Distributing, and they said '5.56 NATO' (on their '20" A2 kit', I didn't ask about the others)...

Also, some (Hesse, IIRC) specifically say 'NO MILITARY AMMO'... I'd guess that means 'we chamber for SAAMI...

Originally Posted By Sitting Bull: Not completely sure what happened to you, but Winchester ammo is complete shit.  Had some of their super-great Winchester hunting round for 300 Win Mag.  Did an eccentricity test on a couple of boxes and man was that shit ever off.  Some as much as 18mm.  Winchester is shit.  Put it in the same group as most of the Wolf ammo.

i cannot speak for any other Win ammo,
My friends and I all used Winchester Q3131 in our rifles.

The Win Q load is the best commerical 5.56 load out there. Accurate, consistent and clean burning.

Again, we all used high quality factory built rifles made by Bushmaster, Colt, HK, Swiss Arms and Robinson Arms.  

After saying that, I got some new Win 308 brasses. They are indeed crap. All the case mouths are dented and I ended up running all them them through my resizing die.

I have seen some of the articles written about this difference with the .223 and 5.56 chambers.  One question I wanted to find an answer to was whether or not a Ruger mini 14 will handle 5.56 ammunition.  When I asked my local gunstore owner, he said there should be no problem with it handling this ammo.  I have held off using any surplus ammunition in the mini 14, because I just wasn't sure whether to trust it.  What are the expert opinions here?  

(Discussions like this is why I learn so much more about firearms at this board, than just about any other place.  Thanks)

Quoted: I have seen some of the articles written about this difference with the .223 and 5.56 chambers.  One question I wanted to find an answer to was whether or not a Ruger mini 14 will handle 5.56 ammunition.  When I asked my local gunstore owner, he said there should be no problem with it handling this ammo.  I have held off using any surplus ammunition in the mini 14, because I just wasn't sure whether to trust it.  What are the expert opinions here? (Discussions like this is why I learn so much more about firearms at this board, than just about any other place.  Thanks)

I have put thousands of 5.56mm rounds through my mini 14 no probs. I have been told it is chambered 5.56mm.  
Ranch Rifle....

So if my OLY M4 says 556 on the barrel, I should not assume that it is chambered for the Nato spec ammo...just .223???

My OLY says 5.56 on the barrel also. Is this true or is it a .223 chamber?

Quoted: Quoted: I have seen some of the articles written about this difference with the .223 and 5.56 chambers.  One question I wanted to find an answer to was whether or not a Ruger mini 14 will handle 5.56 ammunition.  When I asked my local gunstore owner, he said there should be no problem with it handling this ammo.  I have held off using any surplus ammunition in the mini 14, because I just wasn't sure whether to trust it.  What are the expert opinions here? (Discussions like this is why I learn so much more about firearms at this board, than just about any other place.  Thanks) I have put thousands of 5.56mm rounds through my mini 14 no probs. I have been told it is chambered 5.56mm.   Ranch Rifle....

i had a kmini 14 ranch and 9 out of 10 5.56mm cases would split at the neck

OK, wow, a lot of questions here... First off DJS, glad you are ok, sorry your rifle isnt. While it is true that ASA uses the .223 SAAMI chamber, and you were using 5.56 ammo, this would be the first KaBoom ever reported here or elswhere to anyone knowledge shooting 5.56 ammo in a .223 chamber. I am going to post a link to this in the ammo forum, some of the people there might really like to see this and give their opinion.

As to which manufacturers use which chamber... man, its a cluster. And it is hard to know for sure sometimes by just looking. Also, a few manufacturers just changed in the last couple years... Here is the most recent break down I have. This should be the real deal.

Armalite
All older Armalite and Eagle Arms will be .223 SAAMI. In November 2001, Armalite changed to 5.56 chambers on all barrels except the stainless steel barrels. 5.56 chambered barrel will have an "N" stamped into the barrel under the handguards, near the barrul nut. (Attention Armalite, this was a dumb place to put the stamp.)

ASA
All chambers are .223

Bushmaster
All Bushmaster barrels will be 5.56 chambers with the exception of their DCM and Varminter barrels. Possibly the new Stainless barrel as well, but I am not certain.

Colt
All chambers will be 5.56

DPMS
All chambers will be 5.56 even though they mark them .223!!! Talk about confusion!

Hesse
Unsafe at any speed all chambers are .223

Olympic
Olympic used .223 chambers even though it has been reported they were marking 5.56. So if you have a 5.56 marked Olympic, it may not be 5.56. In summer of 2001, they switched to the 5.56 chamber, but I dont think they marked the barrels differently. If your Oly was built/bought before 2001, you have a .223 chamber no matter what it may be marked.

Proffessional Ornance
All chambers are .223

Rock River Arms
All initial chambers, including the 2001 LEGP rifle have the .223 Wylde Chamber. RRA recently started offering chrome lined 5.56 chambers as well. So they are offering both. If you want the 5.56, which is genrerally a good idea, please specify when ordering. I am not sure if their 5.56 chambered barrels are marked any different. But you should be able to notice the chrome lined chamber, and this will indicate a 5.56 chamber.

Wilson Combat (not to be confused with Wilson Barrel Manufacturers)
All initial barrels were .223 but they switched to 5.56 in the summer of 2000

Quoted: Rock River Arms All initial chambers, including the 2001 LEGP rifle have the .223 Wylde Chamber.

OK.  In this thread I have a question that relates, sort of...  I have had issues using South African Surplus with my RRA since I got it.  The new Swiss surplus runs like a charm.  Would anyone have some suggestions for a guy who simply wants to have a rifle that runs when he asks it to?
(i wouldn't have bought so much of it, if I would have known better.  30 successful rounds does not a good ammo test make...  Note to self, empty multiple mags before assuming the ammo works well in your weapon.)

thanks
wannabe

Quoted: Places like JT and Model 1 most likely have a mix of each, most likely .223. These places generally get whatever they can.

new-arguy...I appreciate the work and the detail you have provided here and wanted to comment only on this part as it relates to J&T.  I have no interest in the company, but I used one of their kits for my parts gun and have only run Lake City XM193 and some SA through it.

Although I was not well educated about the differences in .223 SAAMI and 5.56 NATO chambers when I built, I must rely now on what my experiences have been with NATO spec ammo and the assurances of J&T Distributing.

www.ar15.com/forums/topic.html?id=121448

Now, with that information in hand and all that said - I would encourage anyone who contemplates buying or building an AR-15 and wishing to shoot NATO spec ammo to determine the chamber specification prior to the purchase...and in writing.

KBs do happen.  I hope I never have to use the weapon defensively, but at least my aim will not be altered from a flinch caused by a questionable chamber issue.

Jim

asked on the oly site (OA2) and was told that about three yrs. ago they went to the 5.56 NATO chamber in the button rifled barrels, and 223 chamber in the SUM broach cut barrels.

I just recently purchased one of the M4 style RRA barrels from Pete in NH -  is there any way to know what kind of chamber it has?

Sundrop, thank you for pointing out this error, I'm alsways looking for better info than what I have. I will edit.

Snoh, Tom from Oly was here a few months back and made the same claim in a post. that the switch was like three years ago. However, I asked if the switch was made then, why was the announcement made summer 2001? He never replied. So, until there's an answer, I can still only go by when the announcement was made. Not to mention that even if you bought a Oly after this announcement, you still may not have the 5.56. There were a lot of older .223 barreled Olys in shops all over the place. So again, Only the newest Oly's will have them.

Well I thank you guys for all of the answers, much better than me figuring it out on my own...now I want a fulton armory liberator M4 upper...
anyone want an oly arms PCR-10, or a quasi-blown-up ASA compensated M4 upper???




PS now that I know how to use spell check it is great...

new-arguy, I would also like to thank you for providing the chamber info - very helpful.

I do have a question, though.  Are you sure the 2001 LEGP rifles have the Wylde chamber?  Castle arms and RRA specifically stated that they were 5.56x45 Nato chambers.  I really researched it since I bought three of them.

Love them, btw.

Would have preferred chrome lined, but they were a great value.

more info here:

www.ammo-oracle.com/

home.sprynet.com/~frfrog/miscelld.htm