I was wondering if a muzzle brake on a 14.5" barrel would affect ballistcs in any way? Is a brake really needed on a AR15?

lots of info for such a short question.. but i will try
the answer is yes but not always in a bad way, it will effect the barrel vibrations natural frequency, the exit turbulance, and the bullets impact point. all of this is neither good or bad for accuracy. the repeatablity is what counts. if it is the same again and again the bullet will hit the same spot... when its dirty it will not shoot the same as when its clean.
it is not realy needed and often is a severe detriment. the noise it causes the shooter to experience is very evil. and the 223 is so mild in recoil it wont make a hoot of difference at any range the 14 inch barrel is good for...pat