British Bomb, 250 lb GP, Mk 4, Mk 5, Mk 6
Mk IV - The body consists of a hollow steel casting open at each end. The nose end is internally threaded to house the exploder container, which is locked in position by a locking screw. The tail end is shaped to take the tail cone, and is provided with four equally spaced supports, which locate the spring clips on the tail. A male base plate threads into the after end of the body and has two threaded holes to receive the transit base plate.
Mk V - The Mk V Bomb is the same externally as the Mk IV, but is fitted with a central exploder tube instead of the exploder containers at the nose and tail. This bomb does not take a nose pistol, but uses only the No. 17 Long Delay Pistol. The nose opening is filled by a nose plug.
The No. 2 Mk 1 Sheet-Metal Tail is attached to the body by four spring clips. The tail consists of a tail cone with a cylindrical tail strut attached to it by four fins. The spring clips are fitted to the base of the cone, which is slotted to engage the locating pin on the bomb body. At the apex of the tail cone is fitted a bush, locating one end of the arming spindle, which is supported at the opposite end by a diaphragm at the base of the tail cone. The inner end of the arming spindle has an arming fork attached to it which engages the arming fork of the tail pistol of the bomb.
The bomb has a single suspension lug secured to it by four countersunk screws.
The Bomb Mk V was manufactured to use up existing stocks of the Pistol No. 17 (long delay), which is too long to fit in the Bomb Mk IV.
Tail fins are usually painted red when a time pistol is used.
The Bomb Mk 6 is made in the US and uses fuzes manufactured there to British designs: Nose Fuze Mk 7, M3, and Tail Fuze Mk 5, M1.