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michael80 12-11-2012 02:46 PM

difference between 223 and 5.56
What is the difference between 223 and 5.56 in all the conversations I have had with the people I work with I have got 15 different answers and none make any sense to me can some one please inform me properly.

silverado113 12-11-2012 02:49 PM

It has been covered but, The primary difference between .223 Remington and 5.56 is that .223 is loaded to lower pressures and velocities compared to 5.56. .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 (throat) area as well as slightly shorter headspace dimensions compared to 5.56 mm "military" chamber specs, which contributes to the pressure issues.

jcd390 12-11-2012 02:57 PM

I was wondering the samething, thanks Silverado for the explanation.

JTJ 12-11-2012 03:07 PM

Siverado got it right. The problem is mostly in the chamber. Most guns would shrug off a 10% over pressure but that 10% can climb to catastrophic in the wrong chamber configuration.

silverado113 12-11-2012 03:10 PM


Originally Posted by jcd390 (Post 1047791)
I was wondering the samething, thanks Silverado for the explanation.

You're welcome.

Sniper03 12-11-2012 03:14 PM


They are not the same. The Throat on the 5.56 Chamber has a longer lead. While a "True 223 Remington Chambers lead is shorter. The Head Space on both are the same but the Chamber Lead is different in length. One should never shoot a 5.56 NATO round in a "True" 223 Remington Chamber" This is very obvious if you were to check the Chambers of both with a Throat Erosion Gauge. If you will go here in the Forum and find a Thread by me dated 8-23-11 Entitled Throat Erosion Gauge you will see pictures of the Throat Erosion Gauge and it's use. With the Throat Erosion Gauge inserted into the Receiver and looking straight down at a 90 degree angle as shown the "True" 223 Remington would only insert roughly before the First Line on the Throat Erosion Gauge from the tip of the gauge that is in the chamber and throat of the barrel. If it is a 5.56 NATO Chamber it will insert in until the the second or second and one half line prior to the third line. Some manufacturers have a slightly more open lead in their 5.56 chambers. Please see the Thread listed above! There is also one other issue. 5.56 Ammunition has higher pressure than commercial ammunition. Bottom line do not shoot 5.56 NATO Ammunition in a Remington 223 Chamber. All prominent name brand AR Rifles are 5.56 NAT0 or a Wylde Match Chamber which will shoot 5.56 equally as well.


jjfuller1 12-11-2012 03:26 PM

what they said^^

its kinda like a cars seatbelt, you wear it because something could happen. does it always happen no.. but it could. thats why we always advise to not shoot 5.56 out of a .223 chamber... but a 5.56 chamber can shoot both safely

michael80 12-11-2012 04:07 PM

Thank you very much for passing on your knowledge.

303tom 12-11-2012 05:00 PM


jjfuller1 12-11-2012 05:09 PM


Originally Posted by 303tom (Post 1047897)

false.. even if you dont like the idea of non interchangability.

check all the measurments.. even though very little, there is a difference.

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