Quote Originally Posted by spencerhenry View Post
how many people here believe that 223 and 5.56 are NOT actually the same?

just wondering too, how many people KNOW the difference between 300-221/ 300 whisper and 300aac?
A. On the outside the 223 and 5.56 are the same. The brass can be the also be the same, depends on the brass manufacturer or lot number and manufacturer of brass. The chambers (throat area) are different. The loaded ammo is also different. The 5.56 spec is much higher than 223.

b. The 300 Whisper, in its original form, has a thinner neck and corresponding chamber as the parent case is the 221 Fireball. Some early 300 Whisper chambers have an OAL case length of 1.400. This is way longer than the Blackout. 300 Whisper (what you see now) part two has a thicker neck/chamber to allow the use of cut down 223 brass. All flavors of the Whisper have a much shorter throat than the Blackout.