Shooting 5.56mm in .223 Chamber Question

I'm getting a Ruger M77 Hawkeye bolt rifle chamber for .223 rem and was wondering if it's ok to shoot LC 55gr. 5.56mm through it. Bud's online gunshop is listing .223rem/5.56mm for this rifle but Ruger website does not list 5.56mm.

See: http://www.saami.org/specifications_and ... ations.pdf

It says it is UNSAFE to use 5.56 ammo in a 223 rifle!

This is a mirror of the original AR15.com ammo oraclle before "smart people messed it up trying to make it fancy... It is somewhat dated but very accurate:

http://quarterbore.com/ammo-oracle/

Note that the 5.56 ammo has higher pressure and a longer throat then the 223 does.

I never use 5.56 ammo in my 223s!

I think that is good advise. You could probably get away with it in an M77 with the primary extraction of a full size bolt action, but pressures would be higher than they should be. I fired 5.56 South African surplus round in a T/C Contender Carbine ONCE. I had to use light taps on a cleaning rod to extract the case. That tells me something.

That particular load is safe, because its .223 length and set at .223 pressures. The 5.56 Tracer (XM856) round is the one that is longer and higher pressure and should not be shot in a .223 chamber, also any loads that are longer than 2.25" OAL should not be shot in a .223.

Most .223 bolt guns have a 1-12 twist and won't shoot the 55 grain and up bullets very well anyway, you are better off shooting the various 45 grain bullets.

mattsbox99":3gwgmnfk said:

Most .223 bolt guns have a 1-12 twist and won't shoot the 55 grain and up bullets very well anyway, you are better off shooting the various 45 grain bullets.

Click to expand...

According to Ruger's website, the .223 Hawkeye has a 1:9 twist.

1:12 works just fine for 55 grains (common "white-box" generic ammo). Heavier, not so much.

I'd think a M77 .223 would handle 5.56 just fine. If you have any doubts or problems, it shouldn't be much problem to run a 5.56 reamer into the chamber. But I wouldn't even bother with that unless you experience some specific problem.

I would think that Ruger would specifically say don't shoot 5.56 in the rifle in big read letters in the owners manual if it was a problem. Might even put a big red tag on the rifle.

I like the advice about not shooting 55 grain ammo in a 1 in 12" twist rifle, despite the fact that the original M16 was a 1 in 12" twist rifle and was produced like that until the 1980s (tens of millions of rifles distributed around the world) and that the military used 55 grain ammunition.

Personally I would use 5.56mm ammo unless it jammed the rifle. I buy 5.56mm ammo and shoot it in all of my guns, tens of thousands of rounds later... I'm still alive.

Quarterbore is correct, it's not recommended. Here is one of the better write ups I've come across about shooting 5.56 in a 223 chamber. SAAMI does recommend AGAINST this combination. Several factors come into play and the chamber differences are cited as the biggest issue. Also, 5.56 loaded to NATO specs is a typically a hotter round which can also lead to unsafe increases in chamber pressure. And, if you happen to reload, the case volumes a different a 223 load in a 5.56 case can also go boom.

http://le.atk.com/pdf/223VS556.pdf

Here is the SAAMI unsafe combinations which says not to shoot 5.56 in a 223 chamber.

http://www.saami.org/specifications_and ... ations.pdf

piratedude":1xgg5hwh said:

I like the advice about not shooting 55 grain ammo in a 1 in 12" twist rifle, despite the fact that the original M16 was a 1 in 12" twist rifle and was produced like that until the 1980s (tens of millions of rifles distributed around the world) and that the military used 55 grain ammunition.

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Original twist of the AR rifles was 1:14, which worked just fine with 55 grainers, except USAF discovered that accuracy dropped off in the subzero temperatures of Alaska, so they had it quickened to 1:12. Millions of shooters (including me) have used 55 grainers in 1:12 for over 40 years, with good (even great) accuracy and no problems at all.

Turbobuddha":2e1xiizy said:

Quarterbore is correct, it's not recommended. Here is one of the better write ups I've come across about shooting 5.56 in a 223 chamber. SAAMI does recommend AGAINST this combination. Several factors come into play and the chamber differences are cited as the biggest issue. Also, 5.56 loaded to NATO specs is a typically a hotter round which can also lead to unsafe increases in chamber pressure. And, if you happen to reload, the case volumes a different a 223 load in a 5.56 case can also go boom.

http://le.atk.com/pdf/223VS556.pdf

Here is the SAAMI unsafe combinations which says not to shoot 5.56 in a 223 chamber.

http://www.saami.org/specifications_and ... ations.pdf

Click to expand...

Ruger says it's fine to shoot either in their Mini's. So what is the problem?
The company says it's ok, then it's ok.

Just for the record 5.56 AMMO does not have a longer THROAT. The throat is in the rifle/pistol and is what the manufacture cuts it with the chamber reamer. Throat has nothing to do with ammo itself. It is true that chambers cut to 5.56 specs will usually have a longer throat than ones cut to .223 specs. This is to help avoid high pressures with different ammo loads etc. But again it can vary in the .223 depending on the manufacture and reamer used.
There have been millions of rounds of 5.56 ammo shot in .223 chambers without adverse effects for what it is worth. May not be reccomended by some but it is done. I will not choose a side on the forum.

gatorhugger":g59p43x7 said:

Turbobuddha":g59p43x7 said:

Quarterbore is correct, it's not recommended. Here is one of the better write ups I've come across about shooting 5.56 in a 223 chamber. SAAMI does recommend AGAINST this combination. Several factors come into play and the chamber differences are cited as the biggest issue. Also, 5.56 loaded to NATO specs is a typically a hotter round which can also lead to unsafe increases in chamber pressure. And, if you happen to reload, the case volumes a different a 223 load in a 5.56 case can also go boom.

http://le.atk.com/pdf/223VS556.pdf

Here is the SAAMI unsafe combinations which says not to shoot 5.56 in a 223 chamber.

http://www.saami.org/specifications_and ... ations.pdf

Click to expand...

Ruger says it's fine to shoot either in their Mini's. So what is the problem?
The company says it's ok, then it's ok.

Click to expand...

You are comparing apples to oranges here. Bolt rifles will generally have a shorter throat then AR, Mini style rifles. Now because of that shorter throat, when you use the 5.56 round(which already is loaded to a higher pressure then average .223 ammo), you are going to get an even bigger increase in pressure. I would not shoot 5.56 in a bolt rifle. It may be fine for a few rounds, it may be fine for a few hundred rounds, but it is going to be a lot harder on the equipment weather you think it or not.

Jon

And then there is the matter of exactly what is "5.56" ammo?

Anything military (surplus, etc.) can be presumed to be possibly (though not necessarily) loaded to full 5.56 pressures. But what of common "white box" budget-line ammo loaded by all the major manufacturers (Winchester, Remington, Federal)? It's supposedly loaded to old-school 5.56 M193 specs (55 @ 3250, IIRC), but it's all marked ".223" or ".223 Remington" on the box. I've never seen a box of the stuff with any warning on it such as: "WARNING: Although it says .223 on the box, this is really 5.56 stuff and should NOT be fired in your civilian .223 rifle."

ive done it for years and never had one lick of trouble. Not even so much as a flattened primer or sticky bolt lift.

Only the Tracer round is loaded to the higher pressure and requires the longer leade. Every other 5.56 is loaded to the standard .223 pressure and length, only the 80+ grain bullets are loaded out to the long length and you won't see that stuff in factory ammo.

I've seen it tested with Pressure Trace equipment in multiple guns.

The SAAMi Unsafe Combinations list has some strange stuff in it, like saying it is unsafe to fire a 338 Winchester Magnum cartridge in a 300 Savage rifle.

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223 vs 556


Looks like they have the same average pressure:

Lowest pressure for combat-type 5.56 is 50,250 PSI. Highest is 55,000 PSI.

Download the ARMY AMMUNITION DATA SHEETS
SMALL CALIBER AMMUNITION TM 43-0001-27 at:

http://www.ammoinfo.com/modules.php?nam ... tit&lid=10
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SAAMI pressure for 223 is also 55,000 PSI.

http://www.handloads.com/misc/saami.htm
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And looks like they have the same maximum:

"According to the official NATO proofing guidelines the 5.56x45mm NATO case can handle up to 430 MPa (62,367 psi) piezo service pressure. ...This is equal to the C.I.P. maximum pressure guideline for the .223 Remington ..."

http://en.wikipedia.org/wiki/5.56x45mm_NATO
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I have a collection* of articles from Rifle and Handloader magazine. There is an undated article on the 223 written by Bob Hagel. The first three paragraphs are about the lower pressure military cartridges, required for the M16 and AR15, and how reloading to bolt action rifle pressures can significantly improve the cartridge's performance.

*Varmint and Small Game Rifles and Cartridges
Wolfe Publishing Co. 1993


Bruce

As I said above, I do not do it myself BUT if someone is determined to do it please also note that you need to be very careful if you reload as SOME 223 brass is significantly weaker in the case head then 5.56 brass. The big example is Federal (FC) 223 brass as used on American Eagle ammo. That works fine with their load BUT if you try to load that to hotter 5.56 specs you may well experience case failure and over the years I have seen pics of AR-15s that became hand grenades from the failures!

For me, I do not take the chance and I use or reload my 223 ammo for my 223 varmint rifle. I use either 223 or 5.56 ammo in my AR-15s or AK-74s. Just because people may do otherwise, does not mean it is without risks and military surplus 5.56 ammo is not that much cheaper then normal factory ammo and on the contrary it is often more expensive.

My favorite load for my ARs is the Hornady 5.56 T2 TAP. That is without any doubt a load I would not want to send down a normal 223 rifle's barrel but I am sure there is someone out there that will stand tall saying they did it and they still have both eyes!