Use of 5.56 mm ammo in some .223 rifles

Question
I have seen info online stating that 5.56 mm ammunition should not be used in .223 sporting rifles because the throat isn't long enough to accomodate this cartridge, which creates higher pressure in the rifle.  However, I have also been told by local gun experts that it depends which .223 rifle you use, because some, like the Remington 700, have a shorter throat and slower rate of twist (1 in 12) whereas others like the CZ 527 or Savage 16fss, have a faster twist (1 in 9)and can handle the 5.56 mm ammo.  I am looking to buy a .223 rifle and am considering the cz 527 and the Savage 16fss.  I wonder if you could tell me whether in your opinion 5.56 mm ammo can be used in either of these rifles.  Also, do you have an opinion as to the relative performance of these two rifles for that caliber.  I am leaning towards the Savage because of the accutrigger, the weather resistant design, and the availability of left-hand models.

Deborah

Answer
5.56x45 Nato and .223 Remington are the same and completely interchangable. The same way 7.62x54 Nato and .308 Winchester is the same round.
5.56x45 Nato is simply a metric military designation
for the round.  Anyone who telling different simply do not know what they are talking about.  You can chech any reloading manual and it shows them interchanable.
The twist rate of the barrel will have an effect on its ability to stablize the round.  Twist rate of 7 to 1 or less
with a 55 grain round or smaller will tumble at times.
9 to 1 or more will stablize any bullet.

Personally I believe the Savage to be better than the CZ.