(Note: In order to maintain a consistent numbering system across the various countries' designations, and to make searching easier, all Roman numerals on this site are replaced by their corresponding Arabic numerals, e.g. Mk I becomes Mk 1; Mk XII becomes Mk 12, etc).
British bombs are designated by purpose, weight, and mark number. British mark numbers, which are always written in Roman numerals, correspond roughly to the modification numbers used by the US Navy, while the British weight designation corresponds to the US Naval mark number. Minor changes in marks of British bombs are indicated by various symbols, consisting of lower case letters, capital letters, or asterisks.
The classification according to purpose is generally indicated by the initials of the specific type. Thus, there is a series of antisubmarine bombs designated "AS", a series of general purpose bombs designated "GP", semi armor-piercing bombs designated "SAP", aircraft depth charges designated "DC", etc. Occasionally, when no appropriate initials can be used, the complete name of the bomb type is employed in the designation, as "Smoke", "Practice", etc.
Therefore, in order to describe a British bomb completely, the use, weight class, and mark number must be given in that sequence ; e.g., GP 250-lb. Mk V ; IB 30-lb. Mk IV ; Smoke 500-lb. Mk I ; SAP 500-lb. Mk IIC.
The following are the type classifications of British bombs and the initials used to indicate them:
Fragmentation Bombs - F
General Purpose Bombs - GP
Medium Capacity Bombs - MC
High Capacity Bombs - HC
Deep Penetration Bombs - DP
Semi-Armor-Piercing Bombs - SAP
Armor-Piercing Bombs - AP
Antisubmarine Bombs - AS
Aircraft Depth Charges - DC
Buoyancy Bombs - B
Incendiary Bombs - IB
Smoke Bombs - Smoke
Chemical Bombs - LC
Practice Bombs - Practice
Infantry Training Bombs - IT
Target Identification Bombs - TI
Anti-Tank Bombs - AT
OP 1665, British Explosive Ordnance (1946)