I own two Bushmaster uppers.

One is the carbon Fiber one and marked (on the bbl) 5.56 NATO. It is on a Plum Crazy carbon fiber lower.

The second is on a Remington R-15 (made by Bushmaster) and it is marked "multi"
(5.56 & 223 ?) on the magazine housing.

I bought a LOT of LC (Federal) milspec 55 gr ball 5.56 before the panic for 20 cents a round in 20 round boxes. (Now $1.00/round @ my local range).

I have put several 1000 rounds of this ammo, commercial 223 and milspec penetrator loads thru the carbon fiber upper with never a glitch.

The R-15 is new. Ran 20 of the 55 gr Federals thru it yesterday and had two misfires. (otherwise it was VERY accurate, sub MOA)
They both looked like light strikes. One fired on a second try, the other did not.

From past experience with other rifles, I'm guessing headspace as this ammo has never misfired in several ARs and bolt guns.

Any R-15 owners out there with experience like this ?

You know that Bushmaster manufactures the R-15 for Remington. Bushmaster will tell you the .223-stamped R-15s have a hybrid chamber (imagine it's kinda like the RRA Wylde) so as to be more accurate with .223 but safe to use with 5.56. They claim to have never made a factual .223 chambered AR.

Apparently, Remington (remember, they are the retailer) is giving a different response, suggesting that 5.56 should not be used.

Hmmmm......

Anyway, the probable reason for misfires is the thicker primer cup on M193 spec 5.56. I have had the same thing happen (to my K2). It worked fine with .223 and most 5.56, but misfired SA M-193. Problem disappeared when I replaced the hammer spring.

The one comment that concerns me is your mention of using LC M-193 in bolt guns. I trust these bolt guns are stamped 5.56?

Sam

I called Bushmaster and talked to an engineer.

"Hybrid" has nothing to do with the chambering, all it means is that the lower can be used with the different Bushmaster uppers that fit an AR 15 lower. 30 Remington,223 and 450 Bushmaster.

He said the R 15 has a 1 in 9 twist and the leade is set up for not more than 60 gr bullets. The Chamber itself is no different. The hammer spring is also lighter as 223 primers are not as hard as milspec and it gives a better trigger pull too.

The 5.56 carbon fiber upper is 1 in 7 twist for the heavier bullets and the leade is set up for them as well.


In summary, the R 15 is a varmint rifle, the carbon fiber upper is set up to kill people using penetrators in milspec 5.56 ammo.

Insofar as using the penetrators in a bolt gun.
They don't seem to bother a 223 700. They fire fine, are accurate and have no issues with extraction.
No doubt the pressure is higher than sporting 223s but has created no issues.

Leade variations account for about all the differences between .223, 5.56, and hybrids. These differences are important, and they are what we've been discussing. Wylde is not different in principle than the .223 specs BFI is using. The AR community regards them, colloquially, as different chamber specs ("hybrid").

Split semantic hairs if you wish. But M-855 and M-193 service pressures in 5.56 chambers are very, very stout. Pressures will - all else equal - be higher in your .223 chambered bolt gun. Ease of extraction as an excessive pressure indicator has been thoroughly debunked. That you are getting away with it proves nothing beyond a willingness to take risks. But don't take my word for it: http://www.saami.org/specifica...ion_Combinations.pdf

And, again, the weaker hammer spring is most likely the culprit, insofar as misfires with M-193 are concerned.

You are not the first person to call BFI about the R-15 .223 chambering. A cursory search will reveal multiple hits on the topic, with copies of emails sent regarding the hybrid throat.

Sam

Speaking of weak hammer spring, most AR 10's on the market really have AR 15 fire control components in them. What that means is that the hammer, trigger, selector, disconneter, and all the springs are the same as in AR 15's. My point? Well we all know, or should know, that there is a difference in large rifle primers and small rifle primers. Large primers need a harder firing pin strike. The firing pin on the AR 10 is more massive then the AR 15 and an AR 15 hammer doesn't quite give it a hard enough hit to move the heavier mass. All the AR 10 I build have heavier hammer springs. I wish I could find a source for real AR 10 fire control components.

Sam is right about the harder primers and about NOT firing any 5.56 ammon in a genuine 223 Rem chamber. Yeah, you may get away with it a lot of times, but someday it will bite you.

Beg to disagree on "any 5.56 ammo in a 223".
The Federal/Lake City 55 gr FMJ, is EXACTLY the same bullet reloaders can buy. The load chronographs the same as many safe 223 loads.
This particular 5.56 load is perfectly safe in any 223 since the 5.56/223 issue is all about the bullet chosen (as the Bushmaster engineer told me).

Insofar as pressure signs, again I disagree. Absent a pressure transducer, a chronograph, bolt lift, extraction effort, and primer pocket enlargement are all worthwhile indicators of pressure issues in a BOLT action rifle.

I have yet to see any documented evidence that firing a common 55 gr fmj bullet in a 223 in factory or responsible handloads has caused any problems.

Insofar as other military 5.56s in a MODERN BOLT action rifle (like a 700), pressures may be run up but, again, I have yet to see any 223 700 taken apart by a 223. IME, there have been no blown primers, no enlarged pockets, no misfires and no extraction issues. I would not shoot them in any 223 pump or semi auto. Have never owned a 223 falling block (Browning or Ruger), so I can't speak to them.

Mor info:
"Many 55gr bullets use the M193 bullet or VERY similar bullets. For instance, I know that the American Eagle 55gr FMJ bullet will fragment, as well as the Black Hills 55gr FMJ, and the Prvi Partisan 5.56 55gr bullet, as long as they hit their targets at a high enough rate of velocity. "

Go to the Hodgdon website. There is no shortage of 55 gr 223 loads that equal or exceed the Federal/LC 55 fmj velocity. So IMO any "issue" with them is an answer in search of a problem.

The heavier bullet ammo is ...... well using heavier bullets. Do you use the same loads for 200 gr SMKs in your 308 as you do for 150 Hornady FMJs ?

Finally the fired Federal/LC cases drop in and chamber in BOTH Bushmaster uppers. It's the leade not the chamber. The harder primers are an issue in the Remington R-15, but as it's a varmint rifle, it will only see reloads.

Case closed.

Oops, forgot: for the AR10 issue. My DPMS has a Geissel trigger (http://geissele.com/supersemi-automatic.aspx) and has never failed to fire in 260, 308 and 300 SAUM with any ammo including DWM German milspec 7.62 NATO.

Art,

What you are missing is that there is a big different between the 5.56 NATO THROAT and the 223 Remington throat. To simplify it the NATO throat has lots more freebore and more generous dimensions. What this means is that the 5.56 NATO ammo is loaded to fit that throat. In some instances the 5.56 NATO bullet may be right up against the cone of the throat in the shorter 223 Rem chamber throat. That my friend can raise pressure substantially. Now that doesn't happen 100 percent of the time with every rifle and every cartridge. Then again it only takes one time for a catastrophe.

All I can say to you about your Geissel trigger firing everything you've tried is that it has been proven for the accuracy seekers that there is a difference in a light firing pin hit and heavy firing pin hit THAT IN BOTH INSTANCES DO SET THE PRIMER OFF in accuracy. If you research it on the internet you will find it. So my AR 10 is a match rifle and I want the best performance for accuracy. The original AR 10 that Stoner designed has a more robust fire control system then the ones today and definitely then the AR 15's.

quote:

Originally posted by artshaw:
Beg to disagree on "any 5.56 ammo in a 223".
The Federal/Lake City 55 gr FMJ, is EXACTLY the same bullet reloaders can buy. The load chronographs the same as many safe 223 loads.
This particular 5.56 load is perfectly safe in any 223 since the 5.56/223 issue is all about the bullet chosen (as the Bushmaster engineer told me).

Insofar as pressure signs, again I disagree. Absent a pressure transducer, a chronograph, bolt lift, extraction effort, and primer pocket enlargement are all worthwhile indicators of pressure issues in a BOLT action rifle.

I have yet to see any documented evidence that firing a common 55 gr fmj bullet in a 223 in factory or responsible handloads has caused any problems.

Insofar as other military 5.56s in a MODERN BOLT action rifle (like a 700), pressures may be run up but, again, I have yet to see any 223 700 taken apart by a 223. IME, there have been no blown primers, no enlarged pockets, no misfires and no extraction issues. I would not shoot them in any 223 pump or semi auto. Have never owned a 223 falling block (Browning or Ruger), so I can't speak to them.

Mor info:
"Many 55gr bullets use the M193 bullet or VERY similar bullets. For instance, I know that the American Eagle 55gr FMJ bullet will fragment, as well as the Black Hills 55gr FMJ, and the Prvi Partisan 5.56 55gr bullet, as long as they hit their targets at a high enough rate of velocity. "

Go to the Hodgdon website. There is no shortage of 55 gr 223 loads that equal or exceed the Federal/LC 55 fmj velocity. So IMO any "issue" with them is an answer in search of a problem.

The heavier bullet ammo is ...... well using heavier bullets. Do you use the same loads for 200 gr SMKs in your 308 as you do for 150 Hornady FMJs ?

Finally the fired Federal/LC cases drop in and chamber in BOTH Bushmaster uppers. It's the leade not the chamber. The harder primers are an issue in the Remington R-15, but as it's a varmint rifle, it will only see reloads.

Case closed.

Oops, forgot: for the AR10 issue. My DPMS has a Geissel trigger (http://geissele.com/supersemi-automatic.aspx) and has never failed to fire in 260, 308 and 300 SAUM with any ammo including DWM German milspec 7.62 NATO.

I think you're still missing the point. Bullets are not the issue.

SAMMI max pressure for the 223 is 55,000 psi
SAMMI max pressure for the 5.56 NATO is 62,366 psi

As long as your throat gives the 5.56 ammo some running room to start, there is complete compatibilty as 62,366 psi is not harmful to any modern bolt gun chambered for the 223 at 55,000. Most modern pump and semi-auto guns routinely fire rounds above 60,000 psi (think 270 Win in a 742-760 or 300 Win in a Browning BAR).

BUT...if the 223 throat is minimum tolerance and you jam a milspec 5.56 M193 round into the lands you are going to exceed 62,366 by a significant margin. Will it pierce a prime or rupture a case? Unlikely but still possible.

Lastly, milspec primers are hard because the M16-M4 series of rifles have no firing pin return spring. Nor do any of the AR15s. It floats in the bolt and it is possible to have a slam fire with soft primers if the bolt gets dirty and pin sticks. Fairly rare but the answer is as stated above: get milspec hammer springs of you want 100% reliability.

No you are missing the point. The reason the pressure is higher in the SS 109 (if fired in a 223 chamber) is the bullet design and the 5.56 leade is designed to match up with it.

As I SAID, I am NOT shooting any SS109 or similar milspec loads with the heavy bullets in the R-15.

The 55 gr Federal/LC loads have the same ballistics as a max 223 load. The bullet is the same, the velocity is the same ...... so tell me HOW the pressure is higher ?

This is what the official Army specs for the M193 cartridge says:

"3.7.1 Measurement by copper-crush cylinder. The average chamber pressure
o€ the sample cartridges, conditioned at 70 +/- 2F, shall not exceed 52,000 pounds per square inch (PSI)."

NOTE that is PSI NOT CUP ! AND the M193 is the 55 gr fmj load. It will not be "jammed into the lands" as a 223 is throated for bullets of this weight and even a bit more heavy.

In other words the pressure is LESS than a 270 Winchester.

ARs are also made in 204 Ruger. Do you know the SAAMI max for that ?

Have you tried measuring actual bullet contact with the rifling using a Hornady tool ? If you did, you might just find that there is no 55 grain bullet that you could load in a 223 THAT WOULD FIT IN THE MAGAZINE, that would contact the lands.

http://www.hornady.com/store/OAL-Gauges/

As I ONLY hunt big game with Barnes bullets I am VERY familar with seating depth measurement.

I have shot countless "penetrator" rounds in my 5.56 Bushmaster upper (the carbon fiber one) with no ill effects as IT IS DESIGNED FOR THEM.

No 55 gr FMJ lead core bullet loaded to 52,000 PSI is gonna take apart any quality AR. When you can come up with photos of documented examples where the M193 round had been "jammed into the lands" of a 223 AR and taken it apart, I urge you to post them along with all supporting documentation.

AND BTW:

"According to the official NATO proofing guidelines the 5.56×45mm NATO case can handle up to 430 MPa (62,000 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combo has to be proofed at 125% of this maximum pressure to certify for service issue. This is equal to the C.I.P. maximum pressure guideline for the .223 Remington cartridge, that is the 5.56×45mm NATO parent cartridge."

To cut through it, the 63,000 you quote is a PROOF load and is THE SAME as a 223 proof load.

Apples and Oranges.

quote:

Originally posted by artshaw:
No you are missing the point. The reason the pressure is higher in the SS 109 (if fired in a 223 chamber) is the bullet design and the 5.56 leade is designed to match up with it.

As I SAID, I am NOT shooting any SS109 or similar milspec loads with the heavy bullets in the R-15.

The 55 gr Federal/LC loads have the same ballistics as a max 223 load. The bullet is the same, the velocity is the same ...... so tell me HOW the pressure is higher ?

This is what the official Army specs for the M193 cartridge says:

"3.7.1 Measurement by copper-crush cylinder. The average chamber pressure
o€ the sample cartridges, conditioned at 70 +/- 2F, shall not exceed 52,000 pounds per square inch (PSI)."

NOTE that is PSI NOT CUP ! AND the M193 is the 55 gr fmj load. It will not be "jammed into the lands" as a 223 is throated for bullets of this weight and even a bit more heavy.

In other words the pressure is LESS than a 270 Winchester.

ARs are also made in 204 Ruger. Do you know the SAAMI max for that ?

Have you tried measuring actual bullet contact with the rifling using a Hornady tool ? If you did, you might just find that there is no 55 grain bullet that you could load in a 223 THAT WOULD FIT IN THE MAGAZINE, that would contact the lands.

http://www.hornady.com/store/OAL-Gauges/

As I ONLY hunt big game with Barnes bullets I am VERY familar with seating depth measurement.

I have shot countless "penetrator" rounds in my 5.56 Bushmaster upper (the carbon fiber one) with no ill effects as IT IS DESIGNED FOR THEM.

No 55 gr FMJ lead core bullet loaded to 52,000 PSI is gonna take apart any quality AR. When you can come up with photos of documented examples where the M193 round had been "jammed into the lands" of a 223 AR and taken it apart, I urge you to post them along with all supporting documentation.

I didn't see anyone suggest SS109/M855 ever took any rifle apart. Much less old underpowered M193. I did say that in rare cases there have been instances of pierced primers in original 223 chambers firing SS109 milspec ammo. I personally have shot them in mine with no problems.

Current milspec is the 62 gr M855 which is the same as SS109 (except that an enhanced lead free round designated M855AI was adopted in 2010). All are loaded to NATO pressures. Learn to read more effectively. There is also a 77 gr load used by some units (primarily Spec Ops) but not in general issue. There is NO 52,000 psi M193 being produced for US Army combat forces. Maybe a bunch for foriegn contracts or LEO. If the Air Force still uses M16s or M16A1s with 1:12 twist they would have to use M193 because of the slow twist. I'm not current on whether they have swiched to M4s or not.

The 55 gr M193 was superceded in the US Army by the SS109/M855 in 2000. There maybe a few lots of old M193 being used here and there but ALL currently loaded M855 is loaded to NATO spec which is listed below for your edification.

NATO Reference cartridges system

In this system, the ammunition manufacturers, in close cooperation with NATO, have set aside a batch (also termed "lot") of ammunition they consider to be of very good quality and representative of ammunition that should be delivered to the armies in the next following years. This batch is maintained at approved NATO test centres and distributed to the manufacturers involved. When a new batch (lot) is delivered, a set of 20 reference cartridges are fired to see how they behave with the local equipment and with the current atmospheric conditions. Results are then compared to the reference values as maintained by the NATO and correctors (delta values) are computed. Then, the current batch (lot) of ammunition is fired and the correctors are applied on the measured value giving a result "comparable" to the reference itself.

This test is performed under normal conditions but also by simulating extreme polar or desert conditions using special cooling equipment and ovens to cool or heat the tested ammunition to the appropriate temperatures


Calibre

Specific Weapon Detail

Service Pressure Pmax
MPa / (psi)

Proof Round Pressure Requirement
MPa / (psi)

Detailed Requirement for Proof Ammunition



5.56 mm (5.56×45mm NATO)

Designed to chamber NATO ammunition

430.0 / (62,366)

537.5 / (77,958)

Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer[6] or by equipment to Commission Internationale Permanente pour l’épreuve des Armes á Feu Portatives (C.I.P.) requirements



7.62 mm (7.62×51mm NATO)

Designed to chamber NATO ammunition

415.0 / (60,190)

519.0 / (75,275)

Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to C.I.P. requirements



9 mm (9×19mm NATO)

Designed to chamber NATO ammunition

252.0 / (36,550)

315.0 / (45,687)

Pressure recorded in C.I.P. design barrel at mid case position



12.7 mm (12.7×99mm NATO)

Designed to chamber NATO ammunition

417.0 / (60,481)

521.3 / (75,608)

Pressure recorded in NATO design EPVAT Barrel with Kistler 6215 Transducer or by equipment to C.I.P. requirements


I never said it would "take apart" anything. Learn to read. And 52,000 is not a current value, either.

Did you even read Tiggertate's response?

5.56 pressure specs are higher than most any domestic round, including most magnum rifle cartridges. This occurred due to military- specified cartridge power levels (even prior to the SS-109s and M-855) that were very, very difficult to attain with a 5.56/.223 capacity case. It required ball powders and higher operating pressures than originally envisioned by Stoner. NATO M-855 specs codified the pressure realities, but M-193 operating pressures were never far behind. I would not even attempt to reload (or load new brass) to 5.56 power levels.

If you want to learn about this, I'd suggest "Black Rifle" by Ezell and Stevens. Another good source, available online, is the AR15.com ammo oracle which can be downloaded or viewed html.

Everyone responding here wishes to steer you away from potential trouble. Nobody is saying a .223 bolt gun will kb with one round of 5.56. Pressure overloads have cumulative effects related to metal fatigue.

You have been lucky. Now you have been cautioned by a number of experienced individuals who have gone to the trouble of carefully referencing their statements.

But it's a free country.

Sam

quote:

Originally posted by artshaw:
AND BTW:

"According to the official NATO proofing guidelines the 5.56×45mm NATO case can handle up to 430 MPa (62,000 psi) piezo service pressure. In NATO regulated organizations every rifle cartridge combo has to be proofed at 125% of this maximum pressure to certify for service issue. This is equal to the C.I.P. maximum pressure guideline for the .223 Remington cartridge, that is the 5.56×45mm NATO parent cartridge."

To cut through it, the 63,000 you quote is a PROOF load and is THE SAME as a 223 proof load.

Apples and Oranges.

Proof load is 77,958 psi or 125% of 62,366. As I suggested, try to step up your reading comprehension. CIP max allowable and SAMMI max allowable do not always match up. If you reload then you know this is particularly obvious with the 8MM Mauser SAMMI and CIP max pressure ratings. Since you shoot in America I gave the American standard. If the folks in charge of CIP standards want to raise the 223 bar from SAMMI 52,000 to 5.56 NATO numbers, more power to them. Having said that, they may be referencing that the proof requirements of 125% are the same for 5.56 and 223 irrespective of their different max allowable service pressures. Hard to say from such a short sentence.

Tig is right about the proof load. The 60k some load you quoted as being a proof load is incorrect.

More then likely nothing will happen shooting the wrong ammo in the wrong chamber, but you would be amazed at what blowing a primer out or ruptured case can do with just gas going where it shouldn't. Like I said it just takes one time so why risk it?

We have hard data concerning service and proof with respect to M-855. But it's not safe to assume M-193 falls under .223 spec. Most of what passes as "M-193" now is commercial ammo, not loaded to the original VN-era M-193 power level. My surplus '86 SA M-193 chronos 3400 fps from 20" A1s. I've never found a commercial .223 55 gr load that made even 3250 from those barrels.

Possibly, current LC/Federal is loaded to .223 pressure levels and is OK. But this can lead to a dangerous assumption that M-193 is OK in .223 chambers. I would not shoot my SA through a .223 throated gun under any circumstances.

Sam

I think this has been beaten to death.

My LC/Federal 2011 rounds loaded with a 55 gr jacketed lead core bullet produce the same velocity and POI as the same bullet in the same case with a max load of BL C2.

As dense as I am I know not to shoot the green tips in the R-15 223, whereas the LC/Federal 55s are fine in either, except for the hard primers failing once in a while in the R-15.

No one has produced any verified current pressure transducer data or "blown up" 223 ARs from shooting the LC/Federal 55 gr loads.

The green tips work just fine in this pinweight (4.5 pound sans scope/laser/light) 5.56 (also Bushmaster upper).




Nice chatting with you gentlemen !