how to avoid back bouncing

Hello,
i try to make a simple water balloon thrower and use the simple gun and bullet script...
It all works fine but... on collision the water balloon bounces back or sideways before it goes non-physics and "explodes".
Here is the basic of the script, i dont know what to do to make it "stop" faster, help, please

default
{

on_rez(integer param)
{
llSetDamage(5.0);
llCollisionSprite("";
llSetStatus(STATUS_DIE_AT_EDGE, TRUE);
}
collision_start(integer detected)
{
if(llDetectedKey(0) != llGetOwner())
{
llSetPrimitiveParams([PRIM_PHYSICS, FALSE, PRIM_PHANTOM, TRUE]);
MyParticle();
llSetLinkAlpha(LINK_SET,0.0, ALL_SIDES);
// particles();
llSleep(0.5);
llDie();
}
}
}

Make a two-stage bullet (two prims linked together). Put the collision detect on an invisible prim that flies in front of your visible water balloon. You'll have to play with the timing with some of your friends, because there might be client-side / server side differences I'm unaware of.

*---O (* = invisible collider, O = balloon)