I have been wanting a new M&P 15 Sport
For quite a while and finally bought one last week. My question is what is the difference between the .223 and 5.56? It seemed the .223 was a little less expensive than the 5.56, but other than that??????

In a nut shell, the NATO round may be loaded to slightly higher pressure. Some .223 chambered rifles may have throats on the tight side for some NATO ammo with heavier bullets. Some recommend not using NATO ammo in .223 chambered rifles, but many, including myself have done so without issue when using well made bolt action rifles. NATO ammo will usually have crimped and sealed primers, crimped bullets for semi auto use, and may have slightly thicker case walls. Reloading dies and bullets are the same for both. If you reload, using .223 brass speeds up the process, as you don't have to remove the primer crimp.

Larry

Give the man an award. He just conquered the internet in one post. Thank GOD someone finally did it!!

A+ FishinFool. A mutherloving plus.

LOL...Don't hold back

^ What those guys said.

If used in a barrel chambered in 5.56:

.223 = less pressure
5.56 = more pressure

To put it simply, the 5.56 chamber has a smidge more leade than a .223 barrel. Leade is the portion of the chamber before the projectile contacts the rifling of the barrel. That smidge of extra volume is part of the reason why 5.56 chambers can handle the higher pressure. The extra leade allows the 5.56 reamed chamber to reliably chamber ammo made to different tolerances. NATO standard = NATO countries can all share ammo and be friends no matter who made the ammo.

The amount of leade is inversely proportionate to accuracy potential.

A .223 chambered barrel has a shorter leade. The projectile has less distance to travel before contacting the rifling. Less pressure but better potential for accuracy.


5.56 Chamber = 5.56 NATO or .223 Remington ammo.
.223 Chamber = .223 Remington ammo only.

There are exceptions to the rule such as the .223 Wilde chamber.

__________________
-John

Question answered. Thanks

The Ruger Mini 14 therefore must be chamber in 5.56, because it can fire both the 5.56 NATO and .223 Remington ammo.

Is that a correct statement?

http://www****ger.com/products/mini14RanchRifle/specSheets/5805.html

Probably correct. The owner's manual states that they can fire either .223 or 5.56 but it doesn't say which chamber it actually has. It could either 1) be chambered in .223 but designed with enough strength to withstand the higher pressure of a 5.56 round or 2) chambered with the longer leade of the 5.56 or 3) chambered in .223 Wylde (although I doubt this is the case).


From the Ruger website:

The RUGER® MINI-14® RANCH rifles are offered in two calibers: the .223
Remington (5.56mm) cartridge and the 6.8mm Remington SPC cartridge. The
Target Model uses .223 Remington cartridges only.
RUGER® MINI THIRTY® rifles are chambered for the 7.62 x 39mm
cartridge, and can use either standard U.S. military or factory loaded sporting
7.62 x 39mm cartridges manufactured in accordance with U.S. industry practice.
Do not attempt to use any other cartridges in this rifle, even though “7.62mm”
may appear in their names (i.e., 7.62 x 51mm NATO [.308 Winchester]; 7.62
Tokarev; 7.62 x 54 Rimmed Russian, etc.).
The Mini-14 Ranch and Mini Thirty Rifles are designed to use either standardized
U.S. military, or factory loaded sporting cartridges manufactured in accordance
with U.S. industry practice. Always be careful to ensure you are using the correct
ammunition for your rifle. See “Ammunition Notice” & “Warning -
Ammunition,” below.