Army of Two Tips

Riot Shield Melee
Have you ever been in riot shield and your partner has not been hitting the people? Well the easy way to get them is to run up to the enemy with the riot shield equipped and pressing the fire button.However, the shield breaks after approximitely 5 attacks. With i believe 25 kills in co-op riot shield you get an achieement. And with another 25 NON co-op kills you get another achievement.