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Discussion Starter · #1 ·
I have a bit of 5.56 x 54mm Nato penetrator 62gr ammo.

There is a bit of controversy about the difference between .223 Remington and Nato rounds so here is what I know and am ready to be educated from other sources.

My understanding is .223 Remington is loaded to lower pressures than the Nato rounds so you may not be safe firing Guvment rounds through a civilian bolt action rifle.

My other understanding is that in a "black gun" you can fire either .223 Remington or the Nato 5.56x54,

Please let me know if that doesn't compare to your knowledge.
 
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95% there. 5.56 is necked just a short hair different than .223 so they seat differently in the chamber. In the long run, you can shoot .223 in a weapon chambered for 5.56 with no worries, but 5.56 in a weapon chambered for .223 can have negative implications.

As I undertand it, that and the chamber pressure are the two differences.
 

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Its the case specs that differentiate the two and as such the chamber demenions. They are also loaded to different pressure ratings.

The 5.56 NATO chamber is slightly more generous and has a longer throat compared to the commercially loaded 223. The brass on mil-spec cases are generally thicker as well which is why you are recommended to drop your powder charge slightly lower than the minimum listed in a load manual and carefully work your way up when using military brass. The 5.56 is loaded to slightly higher pressures due to the fact that the military often uses full auto weapons, weapons that need to cycle reliably when freshly cleaned or exceptionally dirty and long over due for cleaning and maintenance due to operational commitments. This is why 223 will readily chamber and fire in a 5.56 chambered weapon without any hick-ups.

Now doing the reverse is a bit of a crap shoot. Shooting 5.56 in a 223 chambered weapon will create higher safe working pressures than the weapon may have been designed to take. This usually aint significant but in this sue happy world we live in, you can bet the bank that the manufactures lawyers have this first and fore most in their minds! While the gun wont likely blow up on you, over stressing it with higher than normal pressures can result in metal fatique and ultimately over and extended period of time result in a catastrophic gun failure with enough rounds. Is this likely to happen? Doubtful but that possibility always exist even though gun manufactures try to build a little "fudge factor" into their designs knowing that many in the public will shoot the mil spec ammo in their fire arms despite warnings not to do so in the owners manual. This is why when you do read the owners manual of 223 chambered weapons they often have a disclaimer in there and it often voids the warranty of the gun.

There are some other far more minor issues between the two but those are the cliff note version.
 

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I agree. .223 is not 5.56x54. It's closer to 5.56x45mm, but it's not quite it either. :mrgreen:


Either way. I'll take any someone's looking to give away.
 

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Can't recall the site off-hand, but they had warning pertaining to the same thing when buying ammo. If the barrel says 223 and not 5.56 shoot only 223.
 

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Please correct the 54 in the original post, you can do so by using the edit function. It is a great informative discussion, however I am getting hung up on the 54.
 

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I have always wondered about the differences so this is a great post. Does anyone have any informed thoughts on firing 5.56 in single shot weapons. I have an over under .223/20 gauge and a single shot H&R .223. Both are very robust rifles but if it is creating too much pressure I don't want that.
 

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while the info above is correct - I've always been told to not worry about the difference in any modern firearm that was built in the last decade or so. Now-a-days even your .223 bolt guns, while stamped .223, will handle the extra pressure from a 5.56. If you are really worried, try it, look for any pressure signs - but if your bolt gun was made in the mid 90's or newer you probably don't have to worry about it.

I've (and many others) been shooting 5.56 through .223 bolt guns for years with no issues...
 

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The only difference you need to consider is pressure. The 5.56 case is thicker so the pressure is higher. If a 5.56 is fire in a barrel chambered for the .223 it could stick in the chamber. I am not going to get into the the third option on chamber right now .
.223 will fire in a 5.56 barrel. Most .223 you find is 55gr most 5.56 barrels are 16 inch 1 in 7 twist. The 55gr does not work well in that setup .
Loss of accuracy and as the range increase the bullet will be farther off target and fail to kill.
The 5.56 62gr is designed for the a6 inch 1 in 7 barrel . That or the 77gr if you can find it.
You are right the .223 is not a 5.56 but if .223 is all I have it will have to do in the AR's
Both guns different story that is where the other chamber option came in.

Here you go all typed up for you
http://weaponsman.com/?p=604
 

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The 1 in 9 twist was developed for the M855/SS109 62 gr bullets, 1 in 7 twist was developed for the M856 64 gr FMJTracer. 1 in 7 shoots both 62 and 64 gr, but can overstabilize the 62 gr M855's.

I get a bigger splash on a wet pack milk jug at 200 yards with the 1 in 9 twist vs the 1 in 7 twist.

69 gr SMK/OTM shoot better at 200 out of the 1 in 7, as do the Barnes 62 gr TTSX which relies on expansion as opposed to yawing.

For inside of 100 yards I believe a 1 in 9 twist is better since the bullet has a better chance of yawing than a 1 in 7 twist.
 

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I've heard the same discussion over the 7.62 NATO round and the .308. Generally the same answer applies. A 7.62 rifle can fire a .308 round but you shouldn't fire a 7.62 NATO round through a .308. Generally. If the SHTF, ammo is scarce, and if you have a .223 made by a good manufacturer, then you can probably fire 5.56 NATO rounds with little chance of something going wrong. One thing to keep in mind is that not all ammo is created equal. Even in an emergency, I would be very reluctant to fire 5.56 ammo through a .223 if the ammo wasn't manufactured in the U.S. or Western Europe because of the quality control issue. You might find some ammo that was loaded hotter then the specs call for. On the other hand if there is a group of mindless zombies coming at you and your choice is to use some questionable ammo or a rock........
 

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I fire hot SS109 reloads through a 223 ATI chamber with no signs of pressure on the cases or primer. ATI states it's safe to do so and that the chamber is marked 223 for export to countries who can't have military weapons.
 

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If the barrel is stamped with 5.56 you can shoot either. If the barrel is stamped .223 you don't shoot 5.56 since it won't stand up to the pressure.
Also, my mini-14 is marked .223 but YOU can and I have shot 5.56x45 in it its an old 1986 vintage with 1:10 twist and loves the 62 grain ss109....any bolt rifle in .223 I understand would be strong enough for 5.56 as long as the leade(start of the rifling)does not interfere or set back the longer bullet.and I have fired 7.62x51 in my .308 savage 110 with no problems.this is a debate that will go on forever.
 

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I run into the same thing with my M1A. I only shoot 7.62X51 through it and would like to shoot .308 but have been advised by many not to do it.
I also have had many say it's ok to do so. I look on-line and run into the same thing, it's ok, it's not ok, pressure differences. Who is right?
I have a Saiga .308 that fires either round just fine and would like to be able to do that with my M1A but don't want to destroy that beautiful rifle!
Sorry didn't mean to hi-jack the tread just thought others may have the same question with their 7.62 as they do with 5.56.
 

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Also, my mini-14 is marked .223 but YOU can and I have shot 5.56x45 in it its an old 1986 vintage with 1:10 twist and loves the 62 grain ss109....any bolt rifle in .223 I understand would be strong enough for 5.56 as long as the leade(start of the rifling)does not interfere or set back the longer bullet.and I have fired 7.62x51 in my .308 savage 110 with no problems.this is a debate that will go on forever.
1 in 10 gives a little more wobble to the SS109, and that's a good thing, otherwise it's like getting stabbed with an ice pik.
 

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Ruger states that 5.56 NATO is OK to fire in their Mini 14's even though the barrel is marked .223.
Differences in chamber dimensions, differences in chamber pressure have been noted above.
Firing 5.56 NATO in a .223 Remington chamber will result in a pressure spike of 10,000 psi or more. That's in addition to the 50,000 psi (give or take) of the .223.
Will your .223 rifle suffer catastrophic failure? Probably not. But its service life will be shortened, perhaps considerably.

It is perfectly alright to fire .308 Winchester or 7.62 NATO interchangeably in a Springfield Armory M1A. It is designed to accept both.
 

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Ruger states that 5.56 NATO is OK to fire in their Mini 14's even though the barrel is marked .223.
Differences in chamber dimensions, differences in chamber pressure have been noted above.
Firing 5.56 NATO in a .223 Remington chamber will result in a pressure spike of 10,000 psi or more. That's in addition to the 50,000 psi (give or take) of the .223.
Will your .223 rifle suffer catastrophic failure? Probably not. But its service life will be shortened, perhaps considerably.

It is perfectly alright to fire .308 Winchester or 7.62 NATO interchangeably in a Springfield Armory M1A. It is designed to accept both.
Thanks :)
Really like my M1A!
 

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Thanks :)
Really like my M1A!
My Army Basic Training rifle was the M-14. My stateside issue weapon was the M-14. I had long wanted one of my own.
A few years ago I was fortunate enough to finally be able to afford an M1A.
I found a Standard Model made in 1994, made with mostly USGI parts. Except for reciever (of course) and stock (no cut out for a selector switch). But she looks and fires just like the ones issued to me so long ago. When I hold her in my arms once again I am young and invincible. :mrgreen:
Yes, I too really like my M1A.
Funny thing - when I went to The Pearl Of The Orient (sarcasm) I was issued an M-16A1 and today I have absolutely no desire to own an AR.

Let me give you some links
Best M14/M1A forum - M14 Forum - M14 Forum for M14 M1A Rifles
Some members of that site branched off with their own - Team M14 Forum which is good as well
For M14/M1A refrence, the best is - Different

I am on both forums, same screen name. Come on over!
 
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