Thread: Shooting 556 in a 223

Evening lads,

Looking for a bit of clarification

I hear you can shoot a 223 round in a 556 marked rifle but not the other way round as the 556 has higher pressure.

My question is , Has anyone shot for example the bulk m193 556 ammo in a 223 bolt action ?

Thanks.


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I've shot hundreds through a 223 with no adverse effects. Howa mini, still shoots well.

Yes, including the SS109 and naughty tracer. I still have all my fingers and the rifle a zastava mini.

Shooting 5.56 in a .223 chamber will generate quite a bit higher pressure. Bad idea in an AR which are borderline for lug strength. Something like a howa mini can handle the pressure.

It's not recommended, but I have shot several hundred 5.56 through my howa mini with no apparent damage. Lots of others reporting the same.

If your getting cratered or pierced primers, or are seeing ejector wipe on the back of the brass, I would not shoot them.

Listen to this guy

https://youtu.be/70unU8ntKO4?si=TRV63xACucokunp0

Yes I've shot 5.56 ammo in .223 chambered rifles. Worked fine, but soon found out that milspec ammo does not have quite the same precision as commercial ammo.

General opinion seems to be that pressure will be a bit higher. You won't blow yourself up, but not the best for long term use.

Years ago I tested a bunch of military 556 in a Tikka T3 and an AR-15 with a 223 chamber. I've since lost the data, but from memory I had m193, ss109, and mk262T, the velocities were around 3000-3150. I would happily use that ammo in a modern bolt action.

Interesting. Can we load 223 to 4300bar just off the lands for a CIP proofed rifle e.g. a tikka? Arguably this may be hotter than 5.56.

Originally Posted by Hahn

Interesting. Can we load 223 to 4300bar just off the lands for a CIP proofed rifle e.g. a tikka? Arguably this may be hotter than 5.56.

I think our man Tahr is already hotter than that with some loads lol.... The old norinco yellow box 5.56 was HOT but many of us have fired hundreds of rounds without mishap in .223 marked rifles...mine is also a zastava.

Greetings All,
There are two factors at work here. .223 is loaded to a lower pressure of 55,000 PSI these days and the US load data now reflects this. 5.56 ammo is loaded to a pressure north of 60,000 PSI plus the 5.56 chamber is bigger than the .223 which will push the pressure higher. So it is generally regarded as unwise to fire 5.56 ammo in the .223 chamber. Most of the time you may get away with it but.
In his 1980 report on the .223 Ken Waters chronographed some Korean 5.56 55 grain ammo in his 24" Remington 700. The velocity was 3,421 fps, above any of his handloads some of which were pretty hot. Fast forward a bit and a packet of PMC .223 cartridges with 55 grain projectiles appeared in my cupboard. I chronographed them at well over 3,300 fps in my well used Brno. I just fished the box out. All of the primers are flat and badly cratered plus two of them are pierced. Two don't have primers. Three are unfired and won't be in my rifles.
GPM.

If a rifle can be expected to pass a "proof" round , then it should handle a difference in pressure between a .223 and a 5.56x45 without any problems at all.
Velocity has nothing at all to do with pressure , there are to many things of more importance than velocity .

Originally Posted by grandpamac

Greetings All,
There are two factors at work here. .223 is loaded to a lower pressure of 55,000 PSI these days and the US load data now reflects this. 5.56 ammo is loaded to a pressure north of 60,000 PSI plus the 5.56 chamber is bigger than the .223 which will push the pressure higher. So it is generally regarded as unwise to fire 5.56 ammo in the .223 chamber. Most of the time you may get away with it but.
In his 1980 report on the .223 Ken Waters chronographed some Korean 5.56 55 grain ammo in his 24" Remington 700. The velocity was 3,421 fps, above any of his handloads some of which were pretty hot. Fast forward a bit and a packet of PMC .223 cartridges with 55 grain projectiles appeared in my cupboard. I chronographed them at well over 3,300 fps in my well used Brno. I just fished the box out. All of the primers are flat and badly cratered plus two of them are pierced. Two don't have primers. Three are unfired and won't be in my rifles.
GPM.

Funny how it's us old guys who urge caution. Part of me fancies staying quiet just to increase the odds of hearing from someone who finds themselves looking at a buggered expensive Tikka or somesuch. But nah, Im really not that mean....I just dont understand why anyone would take a decent rifle and put basically crap ammo in it. Maybe if you've got an old beater...I mean, is 5.56 really that much of a thing? I have a Ruger Ranch in 5.56 because I thought, great, it will eat anything. Never had any 5.56 to put thru it in what about 10 yrs. Probably cause I reload near everything but where do you even buy 5.56? And wouldn't it be mostly fmj? Perhaps its all the now redundant stockpiles hanging around post AR15 times....in which case buy a Ruger Ranch in 5.56 with some extra 10rd AR15 mags and keep the nice rifles for what they're intended. Yes?

Originally Posted by Tankd

If a rifle can be expected to pass a "proof" round , then it should handle a difference in pressure between a .223 and a 5.56x45 without any problems at all.
Velocity has nothing at all to do with pressure , there are to many things of more importance than velocity .

Lots of people would agree that there are things more important than velocity, but you are headed into very dangerous territory with your "velocity has nothing to do with pressure" idea . . . I'd love to know how you came to that conclusion because every credible reference out there says there is an exact correlation. It's a fundamental principle of safe reloading.

Originally Posted by Tentman

Lots of people would agree that there are things more important than velocity, but you are headed into very dangerous territory with your "velocity has nothing to do with pressure" idea . . . I'd love to know how you came to that conclusion because every credible reference out there says there is an exact correlation. It's a fundamental principle of safe reloading.

and physics

People go on about pressure being a big boogy man , but the fact remains that a rifle is capable of withstsnding more pressure than they can understand. And the thing that is limiting things is the case , as in the new hybrid cases that are able to contain 80,000+.
But pressure alone does not produce velocity or we would all just use the fastest powder possible or even ram the projectile into the lands hard & fast . So velocity can be manipulated by other factors such as barrel lenght to short and energy is waisted , to long and friction will rob you . By dwelling on presure you loose sight of everything else , so a lower presure can produce more velocity not because of the pressure but because of the amount of time it gets to push the projectile along . Eficency is the answer not push it as hard as it can go !.