Have you seen the newish channel on Freesat: 'Forces TV'? It runs films and documentaries; some of which are actually quite watchable. I saw R Lee Ermey's "Lock 'N' Load" series there the other day and, if you can put up with the bullying Gunnery Sergeant stuff that made his name ("Full metal Jacket"), he produces some interesting weapon comparisons. His brief covers tanks too...
