The animation of the bullet hitting the render has an effectively infinite number of layers....you should be able to have an infinite number of layers in your render instead of just a few if you examine what is happening there and implement it into the "pipeline".
There is no bullet (raycast), what you see is probably bullet explosion hitting wall.
The bullet hit texture you're seeing is one of the few that I haven't converted to black and white (I'm still not sure if it should appear as close as possible like the gun, or if I should leave it as is). My stereogram script is expecting a depth map, so with this colored texture it's effectively random layers. It kinda looks like it has infinite layers, but it's the same ones as the rest of the scene. It's just that the randomness tricks your eyes a bit. With that said, there might be a way to increase the number of layers by adjusting some parameters in the algorithm. But even in the original paper, their example has some obvious layers to it.