Sorry, most of what you said makes no sense.
I have Gun A with Vo of 30m/s shot upward into the air
and Gun B shot towards the ground at the same Vo. . From what height?
Now I know a for A is -9.8 and a for B is 9.8.
No ... gravitational acceleration does not reverse
just because the projectile is shot downward.
As Vo is 30m/s, when it hits the ground, is it 0 m/s ?
It is 0 m/s after it hits the ground.
If you don't believe it, let me drop an anvil on your head.
Does it strike your head with zero velocity?
But I did calc time on Gun A with t=V-Vo/a and get 3.06S. which is from the cliff
to the top of the curve before it falls. . What cliff?
How long after Gun B's pellet hits the ground does Gun A's pellet hit the ground?
I know they hit the ground at the same time.
If they hit the ground together, the question makes no sense.