Here is the full list of all 50 Battlefield: Bad Company achievements worth 1,000 gamerscore.
20 Squad members spawned on you and you didn't die!
Got 10002 kills
Hit hostile helicopter with laser designator
Reached Rank 25
Completed 'Ghost Town' on normal
Completed 'Crash and Grab' on normal
Achieved half of all awards
Climbed to the highest spot in the game
Completed 'Air Force One' on normal
Completed 'Par for the Course' on normal
Got at least one kill in every vehicle
Reached Rank 20
Completed 'Crossing Over' on normal
Found all gold bars
Completed 'Acta Non Verba' on normal
Completed 'Ghost Town' on hard
Found all collectables
Completed 'Crash and Grab' on hard
Played 100 online matches
Found half of the gold bars
Completed 'Air Force One' on hard
Killed 25 enemies in a helicopter
Drove all vehicle types (Jeep, Tank, Heli, Boat)
Completed 'Par for the Course' on hard
Collected 50 unique dog tags
100 kills using vehicle
Knocked down 1000 trees
Took 3 pictures using the image system
Found half of all collectables
Completed 'Crossing Over' on hard
Destroyed 50 vehicles. (containing enemy AI)
Collected 5 unique dog tags
Completed 'Acta Non Verba' on hard
Found 5 unique collectables
Destroyed 200 Walls
Completed 'Welcome To Bad Company' on hard
Knocked down a small forest
Used auto Injector 50 Times
Found one gold bar
Completed 'Welcome To Bad Company' on normal
Completed one mission without dying (any difficulty)
Killed 25 enemies
Destroyed 1000 walls
Placed #1 in a Ranked Match
Reached Rank 8
Used Squad in the menu, found a friend and played one round
There is no parachute, right?
Reached Rank 3
Played one complete ranked online match
(Online) Achieve all the awards