5.56 vs .223 myths and facts

There are enough differences in chamber demensions to raise even more questions.
I think in a nut shell you have to be sure what your shooting and what it is shooting in. The 223/556 is born from the 222, is it not? even back in the day 222 had its warnings of "heavy" bullets. mainly because the the bullet ogive would be crammed into the lands with a heavier longer profile bullet... 222 was generally 55 grains and lighter as was 5.56 when first introduced? Im no expert but to keep things simple i do not put "NATO specified" 5.56 in my bolt gun. al though my bolt gun if I tried to load a 62 grain bullet out to touch the lands there would be little left in the neck....
 
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As a NewB reading the article I get: Exact same dimensions, exact same pressures, exact same everything, but the 556 can be hotter so it may hurt a gun that is only spec'd for 223.

Again as I newb, I was told get a rifle chambered in 556, because that can do both, but one spec'd for 223 should not shoot 556.

In my own brain, I've bought most all 556 for my MP-15, thinking its "hotter", better, faster, etc.
 
A good place to find the differences between the two is a good hand loading book.
You also have to keep in mind the projectile weight. A 1-9 twist barrel is great for 55 grain bullets however a 70 plus grain bullet requires more spin. So you go to a 1-7 twist Even the 62 grain surplus won't give you the best accuracy out of a 1-9 barrel. I have changed all my ARs to 1-7
But back to your orginal question pick up a hand loading book and see if the 556 can be loaded or is loaded hotter.
 
A good place to find the differences between the two is a good hand loading book.
You also have to keep in mind the projectile weight. A 1-9 twist barrel is great for 55 grain bullets however a 70 plus grain bullet requires more spin. So you go to a 1-7 twist Even the 62 grain surplus won't give you the best accuracy out of a 1-9 barrel. I have changed all my ARs to 1-7
But back to your orginal question pick up a hand loading book and see if the 556 can be loaded or is loaded hotter.

This can be tough ....I have not seen many loading manuals with 223 and 5.56 Nato. Loads. My hornady 7th does have a "service rifle" section but they are not "Nato" loads. One member @ out club has a cmp branded AR barrel is stamped 223 Remington. He had all sorts of jams useing. M855. Why? When he shoots his reloads with amax. Bullets no issues? Go figure.
 
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