Night Fighter
From my research, there were two types of extinguishers used in aircraft; Carbon Dioxide and Carbon Tetrachloride. CO2 is most effective with fuel and oil fires, Tetrachloride was more for fabric and wood. This chemical was also used for electrical fires since it didn't conduct. It is my understanding that the hand pump extinguishers were used through 1943 and eventually phased out to pressurized hand held ones.
Carbon Tet gave the most "extinguish" ability per pound of any product then available. It chemically binds up oxygen to rob fire of oxidizer. Downside is that it's not exactly human-friendly. The risk was balanced against being in an unpressurized a/c with available breathing O2 immediately available.
Carbon tet was simple to make, very stable in storage, relatively insensitive to changes in pressure, and temperature.
Contrast that with CO2 bottles. Which needed heavy pressure-proof bottles, the nozzles and release had to be usable from sea level to Service Ceiling, which is a significant range of pressures. The effect of C)2 is to smother a fire adn rob it of O2 and also chilling the fuel source of a fire. If battle damage has occurred, ther ecould be significant air movement within the a/c. Also, at altitude, wher ethe temperature was already very low, the cooling effect of CO2 was decreased, and the pressure change meant some dispersion for the "plume."
So, while it was a proven and known quantity on the ground and apron, it's use while flying had issues.
The Carbon Tet cannisters were often relatively thin as they had to hold little pressure. They were a mix of brass and copper, too, as that could be soldered to make a good liquid-tight seal.
Once AAF went to pressurized a/c, the carbon tet had to go.