The types of firearms likely to be used for criminal purposes are inevitably a reflection of their relative availability. During this century, the United Kingdom has witnessed a number of significant changes in the legislation relating to the possession and transfer of firearms and ammunition. The Pistols Act of 1903 introduced regulations on the sale and use of pistols, as they were seen to be concealable and portable weaponry of the type most likely to be used in crime. The Firearms Acts of 1920 and 1937 effectively established the basis for all subsequent control of firearms and ammunition. Regulations for conventional shotguns, however, were relatively light because of their widespread, socially acceptable uses. The 1968 Act partially rectified the omission, but not until the Firearms (Amendment) Act of 1988 did shotgun regulations become more onerous. The appearance of high firepower smooth-bore guns derived from military close quarter weapons design created a new class of shotgun which was perceived by some as a sinister and socially unacceptable menace. There has been an increase in the use of pistols, as well as increased use of crudely reactivated automatic weaponry which had been deactivated pursuant to 1988 legislation. The article reviews recently upgraded deactivation standards for all types of firearms. Figures, references