When I first saw the pictuer what I noticed right away was the rifling on the seal band for sealing the round against the inside of the tube. I don't know what all those things are called but when I saw that I also remembered reading about drone missiles and I have seen plenty of pictures of sparrows and sidewinders and others and that thing just did not look like any sort of a rocket. It looked kind of like the old deactivated 55 mm arty round I had in my shop for years.
Good catch!
"When I first saw the picture what I noticed right away was the rifling on the seal band for sealing the round against the inside of the tube. I don't know what all those things are called..."
That thing is the obturator ring and performs the function you describe by engaging the rifling in order to spin stabilize itself in flight. The round showed in the original picture is also missing a fuse as it appears it has a shipping plug in place that is removed to screw in the required fuse. Without a fuse, it is not going to explode as designed.