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View Full Version : Is there a difference between 223 and 556?


aslowdodge
09-03-2010, 11:48 AM
I know about the chamber differences and using caution in shooting 556 in a 223 chamber, but is there any difference that make one round better than the other? I notice 556 is more expensive than 223.

Rogu3
09-03-2010, 11:51 AM
Just straight ballistic performance? I doubt it...unless it's high quality commercial 223 vs surplus 556.

Divernhunter
09-03-2010, 11:53 AM
No there is not

HighLander51
09-03-2010, 12:00 PM
Yes, there is, and it depends on how your rifle barrel was chambered. There are a number of different chamber reamers out there, some are good for both, some are .223 Rem and some are 5.56 NATO. Additionally, the pressure is higher on the NATO round.

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

Here is the short version of the article

http://www.ar15armory.com/forums/556-223-Ammunition-Ch-t22582.html

PistolS&W
09-03-2010, 12:14 PM
Yes, there is, and it depends on how your rifle barrel was chambered. There are a number of different chamber reamers out there, some are good for both, some are .223 Rem and some are 5.56 NATO. Additionally, the pressure is higher on the NATO round.

The primary difference between .223 Remington and 5.56 x 45 mm is that .223 is loaded to lower pressures and velocities compared to 5.56 mm. .223 Remington ammunition can be safely fired in a 5.56 mm chambered gun, but the reverse can be an unsafe combination. The additional pressure created by 5.56 mm ammo will frequently cause over-pressure problems such as difficult extraction, flowing brass, or popped primers, but in extreme cases, could damage or destroy the rifle. Chambers cut to .223 Remington specifications have a shorter leade (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

Here is the short version of the article

http://www.ar15armory.com/forums/556-223-Ammunition-Ch-t22582.html

so your saying .223 is not .223x45 like 5.56x45? because if they are the same size cartridge then if you reloaded a .223 cartridge 100% full and seated the bullet on the powder (wich alot of bench shooters do) and did the same with a 5.56 cartridge theres no pressure difference. so my point would be that the most powder you could pack into a .223 would be equivelant to the highest pressure 5.56 and i know that it would still be perfectly safe. but this all assumes the cartridges have the same capacity for powder. but if the cartridges are different in size that poses all whole other pile of questions.

SJgunguy24
09-03-2010, 12:24 PM
http://www.ar15barrels.com/
Look at the tech section and Randall has a couple of PDF files you can look over that has all of the dimensions and you can see the differences yourself. They are different and personally I would not shoot 556 out of a 223 chambered gun.

akjunkie
09-03-2010, 12:26 PM
this should answer alot of your questions.

http://ammo.ar15.com/ammo/project/hist_diff.html

PoofNoEyebrows
09-03-2010, 1:16 PM
so your saying .223 is not .223x45 like 5.56x45? because if they are the same size cartridge then if you reloaded a .223 cartridge 100% full and seated the bullet on the powder (wich alot of bench shooters do) and did the same with a 5.56 cartridge theres no pressure difference. so my point would be that the most powder you could pack into a .223 would be equivelant to the highest pressure 5.56 and i know that it would still be perfectly safe. but this all assumes the cartridges have the same capacity for powder. but if the cartridges are different in size that poses all whole other pile of questions.

A lot of the problem stems from military brass usually being thicker and the fact that it does not conform to SAAMI pressure specs. I think that usually the NATO chamber runs a slightly longer throat (someone correct me if I am wrong) to handle this pressure difference.

CoyoteHunter555
09-03-2010, 1:31 PM
5.56 is bigger- cartridge and a higher chamber pressure

ArkinDomino
09-03-2010, 1:34 PM
I like to "break in" my ARs with M193 and M855. I reload 223 for plinking and to get tighter groups.

VictorFranko
09-03-2010, 1:41 PM
No there is not

http://www.sincitywickedfjs.com/forum/images/smilies/sign0103.gif

CHS
09-03-2010, 1:42 PM
Externally, the cartridges are identical.

5.56 is loaded to higher pressures than .223.

5.56 brass is typically harder and thicker than commercial .223 brass due to the high pressures.

So yes, there are actual ammo differences between the two. They are minor, but important.

aslowdodge
09-03-2010, 1:51 PM
I just got a Spikes wylde chamber so I could shoot both safely and have a bit better accuracy with 223. But I wondered if the performance was better with 556 rounds overall and it sounds like it is a bit better over 223 . Thanks for the info guys

PoofNoEyebrows
09-03-2010, 1:55 PM
I just got a Spikes wylde chamber so I could shoot both safely and have a bit better accuracy with 223. But I wondered if the performance was better with 556 rounds overall and it sounds like it is a bit better over 223 . Thanks for the info guys

Might want to be careful with that too. The Wylde is a hybrid of the two and is still not as deep a throat or size as the NATO chamber. But I agree it is probably safer than just a standard .223 Remington chamber.

dieselpower
09-03-2010, 1:56 PM
I was told, given the same twist rate and gr of projectile, .223 will always be more accurate.

don't freak on me...this is what I was told. Remember...all things are equal, you can not give one a better twist or different weight.

CHS
09-03-2010, 1:57 PM
I just got a Spikes wylde chamber so I could shoot both safely and have a bit better accuracy with 223. But I wondered if the performance was better with 556 rounds overall and it sounds like it is a bit better over 223 . Thanks for the info guys

Depends on what you mean by performance.

5.56 will deliver higher velocities, and so will be "better" as a self-defense type of ammo.

When it comes to accuracy, velocity is meaningless, and well made .223 in a .223 chamber will be more accurate than any factory 5.56.

Just depends on your application. Both are "better" than the other for many different reasons.

bohoki
09-03-2010, 2:01 PM
No there is not

people say there is but i've not noticed any difference

other then it seems to be a certain military specification for different types 55,62grain and .223 can go 40-80 grain loaded hot or weak

CHS
09-03-2010, 2:05 PM
people say there is but i've not noticed any difference


In what measurements are you not noticing the difference?

bomb_on_bus
09-03-2010, 2:52 PM
Pressures, brass thickness, chambering tolerences are the differences between the 2.

As a rule of thumb you cannot shoot 5.56mm NATO cartridges through a .223cal chamber as it is unsafe.

Since your running a wylde chamber IIRC you can run hotter .223 hand loads but still a no go for 5.56mm NATO.

The only similarities between the 2 rounds is they are both fired from an AR-15 and have the same diameter projectile of .224

bohoki
09-03-2010, 3:08 PM
In what measurements are you not noticing the difference?

ive not seen .556 reloading dies

badlandsbutch
09-03-2010, 3:16 PM
Put them side by side. The 5.56 (NATO) is longer than .223 Remington

Colt-45
09-03-2010, 3:17 PM
I'm not an expert but based on my observations, when I shoot at 24oz cans using 5.56 they rip in half. When I shoot at cans using .223 only holes are made.

BigBamBoo
09-03-2010, 3:18 PM
.......

rero360
09-03-2010, 3:41 PM
If you look at AR15s site, the differences are in the thousands of an inch range, in my opinion none being to the point that it would be unsafe to shoot one out of the other.

Think about it, the differences between .38sp and .357mag, .45 Long Colt and .454 Casull are much greater, yet you see people shooting .38s and .45s out of the others respectively all the time, and the dimensional differences are greater than .00x

Me, I'll continue shooting all .223 and 5.56 through my AR without a care in the world.

Purple K
09-03-2010, 3:54 PM
One has two 2's and the other has two 5's

jaytee
09-03-2010, 4:28 PM
If you look at AR15s site, the differences are in the thousands of an inch range, in my opinion none being to the point that it would be unsafe to shoot one out of the other.

Think about it, the differences between .38sp and .357mag, .45 Long Colt and .454 Casull are much greater, yet you see people shooting .38s and .45s out of the others respectively all the time, and the dimensional differences are greater than .00x

Me, I'll continue shooting all .223 and 5.56 through my AR without a care in the world.

I think this is right. I think 5.56 is actually .224 which is why you can use .223 in 5.56 but not the other way round. Like I say I'm not 100% on this so don't hate people if this isn't correct.

luckystrike
09-03-2010, 4:34 PM
if your barrel reads "5.56NATO" then no worries.
.223 and you might want to stray away.

Wherryj
09-03-2010, 5:02 PM
If you look at AR15s site, the differences are in the thousands of an inch range, in my opinion none being to the point that it would be unsafe to shoot one out of the other.

Think about it, the differences between .38sp and .357mag, .45 Long Colt and .454 Casull are much greater, yet you see people shooting .38s and .45s out of the others respectively all the time, and the dimensional differences are greater than .00x

Me, I'll continue shooting all .223 and 5.56 through my AR without a care in the world.

Shooting .357 out of a firearm chambered only for .38 would be a bad idea-if not impossible due to case length. The .357 case was made a bit longer (about 1/8th of an inch if I'm not mistaken) to discourage accidental use in a .38 platform, as not all .38 platforms are built to tolerate the higher pressures of .357.

This would sound like a similar issue. It IS ok to shoot .38 out of .357, but a bad idea to shoot .357 out of .38. It is ok to shoot .223 out of .556, but a bad idea to shoot .556 out of .223.

I will NOT interchange cartridges with my Beretta 92fs, my Browning BDA or my Colt Python, but I DO, however, use the same cleaning kit with these 9mm, .380, and .38/.357 platforms. Bullet diameter isn't the only characteristic that matters.

jackliu239
09-03-2010, 5:03 PM
Now all AR producers make it 5.56NATO chamber, I don't think its even possible to find anyone produce .223 only barrels.

Wherryj
09-03-2010, 5:07 PM
if your barrel reads "5.56NATO" then no worries.
.223 and you might want to stray away.

I guess that my question to the experts would be:

I have an AR-15 chambered in 5.56 NATO. Will that weapon be as accurate when firing .223 REM as a rifle chambered in .223 Rem will be while firing the same cartridge-assuming all other things such as barrels are equal?

I have read some posts stating that there is a little sacrifice in accuracy firing .223 in a 5.56.

CoyoteHunter555
09-03-2010, 5:43 PM
I guess that my question to the experts would be:

I have an AR-15 chambered in 5.56 NATO. Will that weapon be as accurate when firing .223 REM as a rifle chambered in .223 Rem will be while firing the same cartridge-assuming all other things such as barrels are equal?

I have read some posts stating that there is a little sacrifice in accuracy firing .223 in a 5.56.

It is a debatable subject. I believe you can lose some depending. I use .223 in my 5.56 precision AR and get 1/2 MOA at 100yds (at best ;)). There are so many factors that can change results, reloads, factory ammo, etc

Donk310
09-03-2010, 5:54 PM
To me... no difference.

CHS
09-03-2010, 7:50 PM
To me... no difference.

The question wasn't "does anyone notice a difference" between the two cartridges. The question was whether or not they are different.

Yes. They are two very different cartridges in design, pressure, and performance while remaining external dimensionally identical and utilizing the exact same bullet.

luckystrike
09-03-2010, 8:09 PM
I guess that my question to the experts would be:

I have an AR-15 chambered in 5.56 NATO. Will that weapon be as accurate when firing .223 REM as a rifle chambered in .223 Rem will be while firing the same cartridge-assuming all other things such as barrels are equal?

I have read some posts stating that there is a little sacrifice in accuracy firing .223 in a 5.56.

Ive never noticed a differance, but it would depend more on the grain and twist of your barrel. thats more down to the line precision tho.

Donk310
09-03-2010, 9:11 PM
The question wasn't "does anyone notice a difference" between the two cartridges. The question was whether or not they are different.

Yes. They are two very different cartridges in design, pressure, and performance while remaining external dimensionally identical and utilizing the exact same bullet.

Again... (To Me)... no difference.

glockwise2000
09-03-2010, 9:30 PM
One has two 2's and the other has two 5's

good point :rofl2:

IsaacGlass
09-03-2010, 10:20 PM
Again... (To Me)... no difference.

Just like there's no difference between a BMW and a Honda, they are both cars that can take you to your designation (To Me) :D

AR-15 Rep
09-03-2010, 10:43 PM
.223 Chamber pressures 55,000 psi
5.56mm Chamber pressures 62,000 psi

These are from the WIKI info.

Although the .223 and .223 Wylde chambered rifles are made for 55,000 psi they are tested to the 62,000 psi and may work but the next slightly hotter round of 5.56 could ruin your day.

you can shoot the .223 in a 5.56mm chambered rifle but I wouldn't take the chance of a 5.56mm round in a .223 chambered rifle.

You will probably get better accuracy using the correct ammo for the specified chambering. That also depends on the ammo, etc.

tileguy
09-03-2010, 10:52 PM
this can go back and forth all day. to those who say they cant tell the defference prob. have a ar with 5.56 chamber you wont tell the deffrence but i believe if you have an older 223 rifle, lever gun, bolt or semi its not a good idea to shoot the 5.56 because of the pressure. but if you believe that there is no defference go for it but dont cry win something breaks after a couple hundred or just 20 rds of higher pressure ammo in an older gun not designed for that press. iam not an engineer but when people that know this kind of stuff and can test the pressures and tend to be a believer. good luck with what ever side of the fence any one is on

aslowdodge
09-03-2010, 11:20 PM
Maybe I should cal Pikes and ask them what they reccommend. There are a lot of different ideas and many make sense. Thanks for all the ideas though.

akjunkie
09-03-2010, 11:58 PM
Guess Nobody bother reading the info over @ the ammo oracle?

Seems everybody is missing the most important point.

5.56 Military ammo is designed to FRAGMENT.
Fragmentation based on Bullet Construction, Velocity and Twist Rate.

Not all 556/223 created equal.

PistolS&W
09-04-2010, 10:47 AM
Externally, the cartridges are identical.

5.56 is loaded to higher pressures than .223.

5.56 brass is typically harder and thicker than commercial .223 brass due to the high pressures.

So yes, there are actual ammo differences between the two. They are minor, but important.

well then in reality if the 5.56 has a thicker case but the same external dimmensions then .223 if filled 100% WILL have higher pressures just because theres more room. and theres nothing wrong with maxing out the powder capacity.

I think were getting stuck comparing apples to apples because some ammo is sold as ".223/5.56" and it can only be one or the other if they were different in any way.

CHS
09-04-2010, 4:47 PM
well then in reality if the 5.56 has a thicker case but the same external dimmensions then .223 if filled 100% WILL have higher pressures just because theres more room. and theres nothing wrong with maxing out the powder capacity.


If that .223 is loaded that way, then it's way out of SAAMI spec and unsafe ammo. Why would you even bring that argument to the table? That's kinda absurd.


I think were getting stuck comparing apples to apples because some ammo is sold as ".223/5.56" and it can only be one or the other if they were different in any way.

I've *NEVER* seen ammo sold as ".223/5.56". NEVER.

And if there was any ammo like that, then it is likely loaded to .223 SAAMI specs and NOT 5.56 NATO spec, seeing as how dangerous it would be. That's the kind of marketing that gets people killed.