Point of Aim vs Point of Impact

[Scythe Bearer]

I have a mod I am responsible for, and it has a problem.  It is a sniper rifle based off of the normal sniper rifle, only with increased range and magnification.  For all practical purposes, the weapon works as designed with one exception.

The point of aim does not match the point of impact, the projectiles seem to sail.  At long range shots, the shooter has to aim at the targets feet to hit them.   I have tried adjusting the gravity on the projectile to bring the rounds down, but to no effect.

Does anyone have any ideas on what can be done to remedy this problem?