As an addition to the other cohesive guides I will point out that you can find both of these maps (Pitfall and Vertigo) in the action sack playlist as of 24/10/2014.
The max party size for this playlist is 8, which makes these two achievements alot easier to boost as you only need two people with four sets of sticks each to start a game.
-Any gametype with a firearm loadout will work for this achievement.
-Make sure you and the person you boost with both have the map pack downloaded.
-Have the party leader keep searching and backing out until you get a game on Vertigo
-Once the game starts up, shoot the two circles as in the above guides and voila.
*Note I only had to shoot one of the switches for this achievement to pop for me. I know for a fact I had never played on this map in a public game, so this achievement can be glitchy it seems.
Hopefully this helps as I know I had never seen either of these maps once while searching in public games.