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