[Cobra64]

The highest speed the bullet will achieve by simply falling is maybe 10% or less or what it has emerging from the muzzle after the initial shot.

So are you saying that standing at sea level, if I fire my rifle straight up with a 3,000 fps muzzle velocity, that it will attain a terminal velocity of 2,400 fps?

I don't think so. There is no correlation between muzzle velocity and free fall terminal velocity.

[gaijin]

My math makes 10% of 3,000 fps into 300 fps.

But then I said “or less” so a more reasonable number would probably be 150 fps.

But the fact that there’s still residual bullet spin means the bullet is not tumbling, which would have another slowing effect, though we wouldn’t see uniform motion, i.e. the falling bullet would not speed up and slow down.