Question for the gun experts

[Mr. Whiskers]

Sounds a little weird since I was a weapons instructor in the Corps but here it goes. I was always told that a m-16 5.56 round is a .223. Is that true or am I wrong.

[Luck_of_the_Draw]

Different round

[Redraider28]

will shoot in the same chamber according to bushmaster. it has been explain to me that the reason for the confution on this topic is that there are actualy two 5.56 rounds. 5.56X40 i think is one but there is another one so i have heard... its just the first part of the dementions

[TMEC]

What I read is that you can shoot 223 in a 5.56 but not 5.56 in 223.

[Eagles1181]

Same bullet, same case. Just the 5.56 are loaded hotter (or so I have been told). So you should not shoot them in guns not designed for the hotter loads. Again what I have been told.

Eagle

[Extremebowman]

223 "Wylde" chamber will do both if I remember right. Prolly get better answers in ATC than in classifieds

[billfromtx]

Sounds a little weird since I was a weapons instructor in the Corps but here it goes. I was always told that a m-16 5.56 round is a .223. Is that true or am I wrong.

I've shot ball 5.56 out of my 223 a million times and even shot 223 out of my AR when it was all I had...Same same.

Just like a 7.62 Military is the same thing as a 308...

[Bily Lovec]

What I read is that you can shoot 223 in a 5.56 but not 5.56 in 223.

he's closest. cookie for you

[Mike D]

.223 Rem VS 5.56mm

There are a lot of questions about these two cartridges. Many people think they are identical - merely different designations for commercial and military. The truth is that, although somewhat similar, they are not the same and you should know the differences before buying either cartridge.

* The cartridge casings for both calibers have basically the same length and exterior dimensions.
* The 5.56 round, loaded to Military Specification, typically has higher velocity and chamber pressure than the .223 Rem.
* The 5.56 cartridge case may have thicker walls, and a thicker head, for extra strength. This better contains the higher chamber pressure. However, a thicker case reduces powder capacity, which is of concern to the reloader.
* The 5.56mm and .223 Rem chambers are nearly identical. The difference is in the "Leade". Leade is defined as the portion of the barrel directly in front of the chamber where the rifling has been conically removed to allow room for the seated bullet. It is also 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 over 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 Arm and Ammunition Manufacturers Institute) to be an unsafe ammunition combination.



Before buying either of these two types of ammunition, always check your gun to find what caliber it is chambered for, then buy the appropriate ammunition. Most 5.56mm rounds made have full metal jacket bullets. Performance bullets - soft points, hollow points, Ballistic Silvertips, etc. - are loaded in .223 Rem cartridges. Firing a .223 Rem cartridge in a 5.56mm-chambered gun is safe and merely gives you slightly reduced velocity and accuracy. However we do not recommend, nor does SAAMI recommend, firing a 5.56mm cartridge in a gun chambered for the .223 Rem as the shorter leade can cause pressure-related problems.

Winchester Law Enforcement Ammunition

East Alton Illinois

[glen]

higher pressure in 556- they will go bang in both guns but if you are shooting 556 in a gun built for 223 please dont shoot next to me and the kids.

[glen]

what Mike D said

[hntndawg]

This is the important part IMO - coppied from another forum -

While the 5.56 mm and .223 cartridges are very similar, they are not identical. Military cases are made from thicker brass than commercial cases, which reduces the powder capacity (an important consideration for handloaders), and the NATO specification allows a higher chamber pressure. Test barrels made for 5.56mm NATO measure chamber pressure at the case mouth, as opposed to the SAAMI location. This difference accounts for upwards of 20,000+ psi difference in pressure measurements. That means that advertised pressure of 58,000 psi for 5.56mm NATO, is around 78,000 psi tested in .223 Rem test barrels (SAAMI .223 Rem Proof MAP is 78,500 psi so every 5.56mm round fired is a proof load, very dangerous). The 5.56 mm chambering, known as a NATO or mil-spec chambers, have a longer leade, which is the distance between the mouth of the cartridge and the point at which the rifling engages the bullet. The .223 chambering, known as the "SAAMI chamber", is allowed to have a shorter leade, and is only required to be proof tested to the lower SAAMI chamber pressure. To address these issues, various proprietary chambers exist, such as the Wylde chamber[2] or the Armalite chamber, which are designed to handle both 5.56 mm and .223 equally well.

[Bily Lovec]

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

[Mr. Whiskers]

Well, I see now that I posted this in the wrong forum. Thank you for the info. Very informative.

[DerekC]

HMMM. I wonder if I could shoot 5.56 in my heavy barrel single shot .223..in a pinch situation