Certain rifles can fire a bullet with a speed

Certain rifles can fire a bullet with a speed of 965 m/s just as it leaves the muzzle (this speed is called the muzzle velocity). If the muzzle is 70.0 cm long and if the bullet is accelerated uniformly from rest within it,
(a) What is the acceleration (in g's) of the bullet in the muzzle, and (b) For how long (in ms) is it in the muzzle?
(c) If, when this rifle is fired vertically, the bullet reaches a maximum height H, what would be the maximum height (in terms of If) for a new rifle that produced half the muzzle velocity of this one?