5.56 in .223?

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Re: 5.56 in .223?

Post by No1_49er » 05 Aug 2018, 3:55 pm

And this, specifically of the throat.
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Re: 5.56 in .223?

Post by tofu » 05 Aug 2018, 7:07 pm

the thing to note here is that i was asking about the specific hornady rounds i posted in the original message. completely understand there are other 5.56 rounds which just should not be used in 223.

those 2 rounds measure exactly the same except for the projectile and the 223 round is 60gr and 5.56 is 62gr. all lengths and diameters are the same.

when i asked hornady they replied with basically
"we dont recommend using 5.56 in 223 but one of the biggest differences in the 2 rounds is the weight of the projectile where the 5.56 round is designed for deeper penetration purposes."

went to the range today and used the 5.56 in my 223 remington 700 sps rifle and everything was fine. now i also know that generally, it wont reveal any issues/damage straight away and may take some time but i'll keep using both rounds until i run out then i'll start reloading.
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Re: 5.56 in .223?

Post by sungazer » 05 Aug 2018, 7:22 pm

That diagram doesn't really mean much. Starting at the neck size. 2 thou difference as most people know that can vary by a lot more that that on request and is really a measurement made tighter to reduce wear on cases and improve accuracy going small to the extreme on needing to neck turn cases. The military on the other hand make this bigger to ensure for tolerances in manufacturing and dirt. That part of the chamber will not have any potential safety issues.

Then you have some information presented in a very confusing way. which is the throat angle and length of that taper which in one case goes from 0.226 to 0.219 the other going from 0.224 to 0.219

The Military diagram gives an idea of the free boar including the angle at 0.073 and 0.164 add them together for a 0.237 which is very close to the rule of thumb of one calibre.

There is no real way of telling what the 223 diagram has for the free boar. As we know from people measuring the distance to the lands this can vary a lot from manufacturer to manufacturer and model to model.

The angle of the throat is not a big deal either different gunsmiths have different ideas on what "run in angle" should be. Again this is not shown

If anything I think these diagrams go to show that there is not a huge difference.
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Re: 5.56 in .223?

Post by No1_49er » 24 Aug 2018, 8:33 pm

A bit of a late post, but I've been sorting out a dogs breakfast of files in my PC. I knew that there was some info' from Federal, as opposed to Hornady which the OP referred to.
With reference to some who posted that, in essence, chamber dimensional differences between 5.56Nato and 223Rem mean diddly, all I can say is that Federal and SAAMI are not likely to be wrong. Nor Hornady.
Read the cautionary statement. For those who want to call it BS, you don't need to shoot the messenger - take your argument to the ammo makers and SAAMI.

Because of the prohibitions of attaching pdf, doc, txt files etc., I have now other option than to post the text here: -

The Difference Between 223 Rem and 5.56 Military Cartridges

There is a general misperception by the shooting public that the 223 Rem and 5.56 Military cartridges are identical – just different designations for commercial and military – and can routinely be interchanged. The fact however is that, although somewhat similar, they are not the same.

• The cartridge casings of each have basically the same length and exterior dimensions.
• Mil Spec 5.56 ammo typically has higher velocity and chamber pressure than the 223 Rem.
• The 5.56 cartridge case may have a thicker sidewall and a thicker head - to better withstand the stresses generated by the higher chamber pressures. This, however, reduces the powder capacity of the case - which is of concern to the reloader.
• The 5.56mm and 223 Rem. chambers are similar but not identical. The difference is in the “Leade”. Leade is defined as a portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. This portion of the chamber is more commonly known as the throat. Leade in a 223 Rem. chamber is usually .085”. In a 5.56mm chamber the leade is typically .162”, or almost twice as much as in the 223 Rem. chamber.
• You can fire 223 Rem. cartridges in 5.56mm chambers with this longer leade, but you will generally have a slight loss in accuracy and velocity – compared to firing the 223 round in the chamber with the shorter leade it was designed for.
• Problems may occur when firing the higher pressure 5.56mm cartridge in a 223 chamber with its much shorter leade. It is generally known that shortening the leade can dramatically increase chamber pressure. In some cases, this higher pressure could result in primer pocket gas leaks, blown cartridge case heads, and gun functioning issues.
• The 5.56mm military cartridge fired in a 223 Rem. chamber is considered by SAAMI (Small Arms and Ammunition Manufacturers Institute) to be an unsafe ammunition combination and is listed in the “Unsafe Arms and Ammunition Combinations” Section of the SAAMI Technical Correspondent’s Handbook. It clearly states; “In firearms chambered for 223 Rem – do not use 5.56 Military cartridges.” Federal Cartridge is a member of SAAMI and supports this position.
• Federal’s XM193 packaging currently has a warning that states “For use in standard 5.56 Chambers. Do not use in non-standard 5.56 chambers.” This warning is also listed on the XM193 Product Specification Sheet. Winchester also has a similar warning on their USA brand 5.56 ammunition packaging: “Use only in firearms in good condition designed and chambered by firearm manufacturer specifically for this 5.56 ammunition and so marked on the firearm.”
• It is our understanding that commercially available AR15’s and M16’s – although some are stamped 5.56 Rem on the receiver – are manufactured with .223 chambers. Our advice however should be that it is the customer’s responsibility to know what their firearm is chambered for and choose their ammo accordingly.
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Re: 5.56 in .223?

Post by sungazer » 24 Aug 2018, 9:20 pm

I dont know the way you read that/ but the way I read it is that they used to stick to some standards re 5.56 and 223 however they no longer do and there is more than one type of 5.56 and more than one type of 223. (which there is they have both changed over the years) so they then fishing up saying the no matter what is stamped of the rifle or ammo check that it is suitable for that rifle.

That is what I was really saying that the Standards are no longer adhered to as the projectiles have progressed which meant new chambers and twist rates had to be developed, but the standards never changed.
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Re: 5.56 in .223?

Post by Homer » 27 Aug 2018, 5:42 pm

G'Day Fella's,

FYI, here is a link with a short and basic description, of the differences;
https://loadoutroom.com/thearmsguide/is ... -and-5-56/

Hope that helps

D'oh!
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Re: 5.56 in .223?

Post by No1_49er » 27 Aug 2018, 6:18 pm

Yes, that reiterates, almost word for word, what Federal stated in their cautionary statement from (circa) January 2008.
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Re: 5.56 in .223?

Post by sungazer » 28 Aug 2018, 5:29 pm

Another good article is by Berger Not 223 VS 5.56 related but more general to overall reloading. A note that is interesting is that Berger only make one bullet type according to SAAMI Specs.
"these SAAMI standards are in many cases outdated and can dramatically restrict the performance potential of a cartridge."

http://www.bergerbullets.com/effects-of ... to-part-1/
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Re: 5.56 in .223?

Post by No1_49er » 28 Aug 2018, 6:29 pm

SAAMI_as revised 07 May 2018.JPG
SAAMI warning_2018 May 07
SAAMI_as revised 07 May 2018.JPG (79.27 KiB) Viewed 228 times


Contained within that article is this: -

SAAMI COAL Limits Ballistic Performance
It is a fact that the ballistic performance of modern ammunition is directly limited by the SAAMI COAL standards that are currently in place and that rifle manufacturers build to. Even when a shooter understands the implications of cartridge case volume and has a chamber that allows them to load the rounds out long, the rifle itself (having been built to feed SAAMI length cartridges) won’t allow the shooter to do so.

It goes on to say that that is the reason for building custom rifles, i.e. not to SAAMI spec.

And whilst the Berger article isn't related specifically to 223/5.56, the current SAAMI warning, as updated 07 May 2018 is quite clear in that regard.
Don't shoot the messenger - the SAAMI specs are an agreement between the manufacturers of firearms and ammo. I'm simply posting them as found.
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Re: 5.56 in .223?

Post by BRNO_Bigot » 30 Oct 2018, 7:40 pm

I would fire them in MY rifles - because mine are European and they are developed for CIP instead of SAAMI specs. CIP gives both the same specs, so no problem.

CZ answers this question in their CZ USA FAQS if you want to search for it.
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