Barrel (unit) continued to use the same size barrels. In the worldwide oil industry, an oil barrel is defined as 42 US gallons, which is about litres or 35 imperial gallons. Oil companies that are listed on American stock exchanges typically report their production in terms of volume and use the units of bbl, Mbbl (one thousand barrels), or MMbbl (one million barrels) and occasionally for widest comprehensive statistics the Gbbl (or sometimes Gbl) denoting a billion. There is a conflict concerning the units for oil barrels (see ). For all other physical quantities, according to the International System of Units, the
Barrel bomb Barrel bomb A barrel bomb is an improvised unguided bomb, sometimes described as a flying IED (improvised explosive device). They are typically made from a large barrel-shaped metal container that has been filled with high explosives, possibly shrapnel, oil or chemicals as well, and then dropped from a helicopter or airplane. Due to the large amount of explosives (up to ), their poor accuracy and indiscriminate use in populated civilian areas (including refugee camps), the resulting detonations have been devastating. Critics have characterised them as weapons of terror and illegal under international conventions. The earliest known use of barrel bombs