When Your .223 Isn’t a 5.56 and Vice Versa

Saw this over at Guffaw:

The significant difference between the .223 Rem and 5.56 NATO lies in the rifles…

That’s not really surprising. .223 does not equal 5.56. And I do mean that in every sense of the word “equal”. If it’s stamped .223, then it isn’t stamped 5.56. Not so hard to understand.

Does that mean you can’t interchange them safely? In this case, not at all.

So, what’s the actual difference? Chamber? Tolerance to pressure? A plot by ammunition manufacturers to get you to buy the more expensive cartridge? No. No. No.

It’s the throat.

On a .223 Remington spec rifle, the leade [throat] will be 0.085”

And on a 5.56?

The leade in a 5.56 NATO spec rifle is 0.162”, or almost double the leade of the .223 rifle.

Oh, so what you’re saying is that there’s a difference of 5/64ths inch.

I wonder if perhaps there are concerns that after firing 15-25K rounds it might reveal some undue wear on the throat. I’m not at all concerned because the overriding factor is that the lining of the barrel is only good for about that many rounds anyway.

I’m going to keep shooting whichever of the two has the ballistics that I desire for the task at hand.

Though presently it seems the only thing that’s effectively limiting my range time and my desire to knock over aluminum cans from great distances regardless of caliber is the simple question of availability.

Guess I’ll need to spend some quality time with a muzzleloader instead.

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