Guncraft Blocked and Loaded

Another simple achievement if you can find a tank.

Remember to join Xbox Live with two controllers (One signed in as a Guest Account) and select Deathmatch then Host game.

Now use these settings:

Map: Block Gulch (Blood-Gulch in block form)
Game-mode: Deathmatch or Team Deathmatch either works.
Time: Uncheck this box
Kills: Set to 20 (It took 12 before this unlocked for me)
Check unlimited resources if you want, shouldn't matter for the achievement.

Remember to select Apply to save settings.

Launch the game and to the left of each base there is a tank and hover-bike.

Press to enter the tank and use the second controller to run towards the tank. (You may spawn underground however there are steps that lead up)

Now just keep shooting the second account down, this will pop at either 10 or 12 kills may take longer.

Just return to the lobby once done as the stats will still save.

You can easily get this by creating your own map, placing a tank in it as well as 4 blue and 4 red spawn points. Then host a match with 1 more player or guest account and get 10 kills with the tank to pop the achievement.