The flamer is a sort of middle ground between the big guns. It has the shortest range of any big gun, but does quite a bit more damage per shot compared to miniguns. Fire resistance is often lower than normal resistance, so a flamer can usually do more damage to an enemy in power armor than a minigun, and has less danger to the user compared to the BigBazooka rocket launcher. Floaters, especially, have very low fire resistance. The only downside to the flamer is the heavy ammo, which weighs 10 pounds for a cluster of 10 shots.
One can be upgraded into an improved flamer in Fallout 2. It increases the flamer's min damage by 5, and makes it one pound heavier. Loaded with volatile flamethrower fuel Mk II, a flamer can roast enemies at close range, while miniguns destroy targets at medium range, and a BigBazooka rocket launcher annihilates far-away foes.