The primary reason for muzzle rise is that for nearly all guns, the bore axis (longitudinal centerline of the barrel) is above the gun's center of mass, while the contact points between the shooter and the gun (e.g. grips and stock) are often all below the center of mass.

What causes upward recoil?

The backward force from the high speed bullets/air coming out the front of the gun pushes backwards and pivots from this high friction point to give you what looks like an upwards recoil.

Why does handgun give this kick when firing it?

When a bullet is fired from a gun, the gun exerts a force on the bullet in the forward direction. The bullet also exerts an equal and opposite force on the gun in the backward direction. ... Therefore a gun recoils when a bullet is fired from it.