c_trace and USE_BOX and collision-group problems...

ENTITY* bullet_template = { type="bullet.mdl"; }

function can_be_hit(VECTOR* source, ENTITY* targit, ENTITY* shape)
{
	//backup old "me" info
	ENTITY* old_me = me;			//save old "me" so it can be restored later.
	var     old_my_group = my.group;	//save old "me" collision group too.
	me.group = 30;				//set old "me" to a collision group that
							//	is ignored by this function
	//
	//backup old "targit" info
	var     old_targ_group = targit.group;	//save "targit" collision group too.
	targit.group = 30;				//set "targit" to a collision group that
								//	is ignored by this function
	//
	//set "me" to collision-hull of choice
	me = shape;		//set "me" to collision-template for USE_BOX tracing
	me.group = 30;	//set "me" to ignore-able collision group
	//
	//do the trace.  (IGNORE_PUSH should make it ignore group=30, correct?)
	var results = c_trace(source, targit.x, IGNORE_PASSABLE|USE_BOX|IGNORE_PUSH);
	//
	//restore old "me" and "targit" to the way they were
	me = old_me;				//restore old me into "me"
	me.group = old_me_group;		//restore old "me" collision group
	targit.group = old_targ_group;	//restore old "targit" collision group
	//
	return(results);	//return distance to target
}


action player_act()
{
	ENTITY* victim=NULL;	//pointer to selected enemy target
	...
	if((mouse_left)&&(victim))
	{
		var victim_range = can_be_hit(my.x, victim, bullet_template);
		if(victim_range <= bullet_range)	{	shoot();  	}
	}
	...
}