In the Anchorage Memorial service entrance, in the utility room. It requires a Repair skill of 95, or a Repair skill of 35 with the door component from the facility.
In the Arlington utility tunnels. From Arlington Cemetery north, go up a set of stairs on the left then right at the top. It is on a shelf on the right side of the room.
In the car dealership building to the east, on the upper level where there are smaller, ruined vehicles. The coffee table has to be jumped on in the corner to get to there. It is on a generator.
In Franklin Metro utility, through an underwater section of the subway tunnels near a lot of radiation. On a shelf with missiles and darts, etc. Can also be reached from the subway entrance next to Hubris Comics.
On top of a ridge to the north-northeast, directly northeast of the barn with the scavenger's key, on the ground beside a dead mercenary and a dead wasteland settler with bloatflies buzzing around them.
In an ammunition container in the burned out bus near the red railroad car northwest of the building that is north of the office (not the same red car where Dogmeat is found). The key from the random encounter "More Than Just Scrap" can be used, or the lock simply picked (Hard).
In the Capitol Building west entrance, on a table in the dome, where the super mutant behemoth is; this one is likely to have been knocked off in the firefight.
In a room full of weapons on the bottom floor behind a door (Very Hard) or terminal (Very Hard).
Notes[]
Due to a bug, it is possible to obtain infinite copies of the book from a raider in the Bethesda east offices who respawns every 72 in-game hours.
An image of this book is copied onto a slide for the Vault Dweller's Survival Guide. The slide's identifying number is VDSG Plate #619-58.
It is likely that "recipes" is an analogy to combat tactics involving the flamer, presented in a humorous format of a cookbook.
This is the only skill book unique to Fallout 3, as it is not present in earlier games and does not return in Fallout: New Vegas, due to the Big Guns skill being collapsed into Guns, Energy Weapons and Explosives, as well as being replaced by Survival. Nonetheless, the item itself is still present in the resources of Fallout: New Vegas, but is not placed anywhere in-game.
If a player is able to acquire a copy of U.S. Army: 30 Handy Flamethrower Recipes in Fallout: New Vegas and uses it, they will be informed that "Big Guns has been increased by 3" (or 4 with the Comprehension perk). However, this does not actually increase the stats of any weapons in the game.