This could be from a “V” bomber. It has the four housings for the secondary cartridges (on opposite sides of the main body) to incrementaly increase the upwards acceleration of the seat, to enable it to clear the tail.

The conical housing at the right end of the gun fitted into a housing in the cockpit floor. the other end may have the housing for the initiater cartridge, which was spring operated, and held in the safe position by a tapered sear and a safety pin.

This type of ejection gun probably have two tubes mounted one inside the other, fitted inside the cylindrical body shown in the picture.