Either play through this on story progression or from the main menu select the chapter Thugtown and play on easy difficulty.
There is only one pistol which you can use during this chapter and cannot be any other variation of dual pistols here in image below is the correct pistol selected via
Play through the level as fast as possible jumping/rolling and get to the final stage as fast as you can, you can easily pass the whole level with ease until the final section.
Make sure you took into the left as the propeller comes down.
Image below is me entering final area.
The final area is quite tricky once you have removed all the zombies, especially with the 3 large enemies attacking you ripping away your health.
First of all activate the TNT with
My personal strategy was try not to pick up any health packs unless I really needed them, shoot and destroy the explosive barrels as the large enemy passes them.
I also moved around the map anti clockwise while shooting at him, this was my preference clockwise can be just as affective until you have killed your first large enemy.
Finally you will then get 2 more of the larger enemies to kill, keep with the same method obviously picking up any health when needed!
Blast away at both of them trying to take out 1 at a time as it will be easier to control, bearing in mind only to use your pistol as you don’t want to mess up at this point.
Once the TNT has exploded and you walk through the exit area, pop achievement unlocked.