perfect bounce when a bullet hits a wall

I wanna create bullets at runtime with physical features as the following code. As long as the speed increases to a higher enough number, such as 350.0f, 400.0f, 1000.0f etc, the bullet will pass through the surrounding walls without any bounce and any collision, which is not what I want.

Is there a way to set perfect bounce but the speed regardless ?
(the Bounce Threshold is 0, Friction is 0, Minimum Friction Combine and Maximum Bounce Combine)

thanks ~

// bullet gameobject's physics settings
bullet.rigidbody.useGravity = false;
bullet.rigidbody.isKinematic = false;		
bullet.rigidbody.collisionDetectionMode = CollisionDetectionMode.Continuous;
Vector3 direction = (target.transform.position - bullet.transform.position) 
Vector3 directionWithSpeed = changeSpeed(direction);
// to fire a bullet with a force here

public float speed = 100f;
Vector3 changeSpeed(Vector3 src){
	// the problem : there should be a limit on speed
	speed +=10.0f;
	return new Vector3(src.x*speed,0,src.z*speed)

For the bullet you want to use ContinuousDynamic mode, rather than Continuous, and for those objects with which it will collide (such as the wall), use Continuous mode for those.