I do think there is some justification for the poor armament. (granted, another thing they should have been mining the past for..)
but, this was a war of numbers. The aliens were swarming. just too many. the Military could hold its own well enough in a direct conflict. Jets, bombs, etc. but, jets, etc use fuel. Bombs, ordinance has to be produced. the Military could defend its bases, but NOT maintain a supply chain. So, it makes sense all the good stuff, high caliber weapons, rpgs, etc, all got used up in the first few years. They've run out, and now are forced to used lower power weapons. this idea is only really touched on, with the food rations. but would make sense for the ordinance as well. which again.. would be something they should have been getting from the past. Hell that could have been a plot point. Arm the civilians to the teeth with new weapons/ammo, send them to the future. oops they died. well, we don't really care about the people, we just need the weapons. which could have lead into a theme of mining the past to save the future, and causing more harm doing that, then its helping.
