Actually, it isn't uncommon for bullets to be somewhat unstable when they leave the barrel. Generally, there will be some "wobble" of the bullet around the axis of the bullet path as it leaves the muzzle. The nose of the bullet will follow the path axis fairly closely, but the rear of the bullet will spiral around this axis. Eventually bullet spin will cause the base of the bullet to fall in line with the bullet path axis causing the bullet to go to sleep. This phenomenom can lead to some bullets/loads having better accuracy at longer ranges with respect to MOA. The distance that it takes for a bullet to go to sleep depends on a bunch of things, like muzzle velocity, twist rate, bullet dimensions, etc. This has nothing to do with keyholing though, that is a result of little to no stabilization of the bullet as it leaves the barrel.