In your ProjectileData datablock, put isBallistic = True; instead of False;
Then, change the gravMod = 0.0; value, to say 1.0; or whichever value. Test it out and if it falls too slowly, make it a larger number.
AddDamageType("Lasher", '<bitmap:add-ons/ci/Lasher> %1', '%2 <bitmap:add-ons/ci/Lasher> %1',0.5,1);
datablock ProjectileData(LasherProjectile)
{
projectileShapeName = "./shapes/LasherBullet.dts";
directDamage = 50;
directDamageType = $DamageType::Lasher;
radiusDamageType = $DamageType::Lasher;
brickExplosionRadius = 10;
brickExplosionImpact = true; //destroy a brick if we hit it directly?
brickExplosionForce = 10;
brickExplosionMaxVolume = 1; //max volume of bricks that we can destroy
brickExplosionMaxVolumeFloating = 2; //max volume of bricks that we can destroy if they aren't connected to the ground
impactImpulse = 700;
verticalImpulse = 1000;
explosion = LasherExplosion;
particleEmitter = LasherTrailEmitter;
muzzleVelocity = 80;
velInheritFactor = 1;
armingDelay = 00;
lifetime = 4000;
fadeDelay = 3500;
bounceElasticity = 0.7;
bounceFriction = 0.40;
isBallistic = false; //This part here, set it to True instead of False
gravityMod = 0.0; //Then, set this to a Positive non-zero number
hasLight = true;
lightRadius = 10.0;
lightColor = "0 0 0.3";
};