I'm no 13B, but it looks pretty similar to some of the stuff we're using. I would be willing to bet the self propelled is a generation or so behind ours from a technological perspective.
The barrage rockets were 122mm, or a new variation. Very familiar with the 122. They even had a plate that could be screwed on the nose for air resistance which shorten the maximum range when used one at a time, carried in and set up manually by two men. Deceptive as you never knew how far out the launch position was. Watched a bunch of them fly through the night sky, and went off with a bright white flash. Fuel was used behind most of those targets to give a better visual effect for the camera.