I use this collision code:

function remove_bullets();

function bullet()
{
my.emask|=ENABLE_IMPACT;
my.emask|=ENABLE_ENTITY;
my.emask|=ENABLE_BLOCK;
my.event = remove_bullets;
while(1)
{
c_move(me,vector(40,0,0),nullvector,USE_BOX|IGNORE_MODELS);
wait(1);
}
}

function remove_bullets() // this function runs when the bullet collides with something
{
wait (1); // wait a frame to be sure (don't trigger engine warnings)
ent_remove (my); // and then remove the bullet
}

The collision detection definitely works, but can you just tell me how to make the bullet don't detect the gun and the player models in this case