Too fast and the bullet goes pffffttttt.............disintegrates.
What .223 bullet do you think will handle 4,000fps better 35gr V-MAX or a 35gr VG ?
You mean that they claim it is going 4000fps, which is not the same thing as actually doing it. Personally I have seen some Hornady ammo in a different caliber that was overrated by about 230fps. As far as the 223 with light bullets, I have seen some WIN 45gr that was advertised at 3600fps tested, and true measured velocity in a 26" barrel was a mere 3307fps.Hornady is already making 35gr 223 factory ammo that has a 4,000fps Muzzle Velocity