Here is the full list of all 17 Out of Ammo trophies - there are 15 bronze and 2 silver.
10 kills while using a machine gun emplacement
Survive for 25 minutes in a single round
2 kills while possessing a medic or engineer
Survive for 20 minutes in a single round
Survive for 15 minutes in a single round
10 kills while possessing a sniper
Assist 20 enemy casualties
Survive for 10 minutes in a single round
10 kills while possessing a rifleman
Survive for 5 minutes in a single round
10 kills with one artillery barrage
Suppress or kill 7 units with the strafing run
Survive for 30 minutes in a single round
Kill an enemy unit at over 150m
10 kills while possessing a rocket unit
Kill 5 units with a single rocket
Hunt down the hidden targets