How to pass the level of the Dam? (Far Cry)

Tell me how to pass this level? Well does not work... Play on the hardest difficulty and I kill the mobs there with a single blow. The first mob (at the top) I can still get around safely, but then no - catch up and pile on. And the cartridges are just a 10 - lasts for a maximum of one mob. And some there still shooting at me...