four-charge gun

four-cycle / four-stroke

four by four

fingertip formation / finger-four formation / four finger formation

four-barreled anti-aircraft gun

propelling charge (propellant charge)

augmenting charge / incremental charge (of mortar etc.)

four-point barb

four by two

four-groove barrel

four-point

four-stage compressor

four-way valve

four-wheel drive

four-wheel drive truck

four-boss breaker cam

four-stroke cycle

four-step stand

four-stroke engine

Four Tonner (Bedford truck)

gun-charge-projectile combination

L119 light gun (105 mm light gun)

submachine gun / sub-machine gun (SMG; smg)

gun control equipment / gun-control equipment (GCE)

duck gun (duck-gun)

flame gun / flaming gun

gun by gun

blank charge

blaster charge

bursting charge

charge container

charge distribution

chemical composition of propelling charge