Part 6: Firearms and pyrotechnic articles Section 125: Firearms Act 1968: meaning of "firearm" etc.
Section 57(1) of the 1968 Act (Interpretation) defines a firearm as a "lethal barrelled weapon" but does not define "lethal" in this context. It also provides that the definition of firearm includes any "component part" but without defining this term.
	Subsection (2) amends section 57(1) of the 1968 Act so as to define a firearm as: (a) a lethal barrelled weapon; (b) a prohibited weapon; (c) a relevant component part of either a lethal barrelled or prohibited weapon; or (d) an accessory which is designed or adapted to diminish the noise or flash caused by firing a lethal barrelled weapon.
	Subsection (3) inserts new subsections (1B) and (1C)  into section 57 of the 1968 Act. Subsection (1B) defines a lethal barrelled weapon by reference to a threshold of one joule for muzzle kinetic energy. Muzzle kinetic energy is the power of a discharged projectile as it leaves the barrel of a weapon.
	This means that a weapon with a muzzle kinetic energy below the lethality threshold of one joule is not a firearm for the purposes of the 1968 Act. An air pistol (which uses compressed air to fire a projectile) with a muzzle kinetic energy above the lethality threshold but below 6 ft lb (or 12 ft lb for other air weapons) is a firearm but does not need to be held on a firearms certificate by virtue of section 1(3)(b) of the 1968 Act. An air pistol with a muzzle kinetic energy in excess of 6 ft lb, or any other air weapon with a muzzle kinetic energy in excess of 12 ft lb, needs to be held on a firearms certificate. (Converted into SI units, these figures are 8.13 joules and 16.27 joules. The conversion factor from foot-pounds to joules is to multiply by 1.3558.)
	New section 57(1C) provides that the definition of firearm is subject to new section 57A of the 1968 Act (exception for airsoft guns - see below).
	Subsection (4) inserts a new subsection (1D) into section 57 of the 1968 Act which defines a relevant component part of a lethal barrelled weapon or a prohibited weapon. The following items are relevant component parts:
	a) a barrel, chamber or cylinder;
	b) a frame, body or receiver; and
	c) a breech block, bolt or other mechanism for containing the pressure of discharge at the rear of a chamber.
	This provision will ensure that those parts that have the potential for criminal misuse are subject to control, whilst not requiring that every pin or screw be listed separately on a firearms certificate.
	These terms are not defined further but will take their commonly understood meanings, namely:
	Barrel – that part of a firearm through which a projectile or shot charge travels under the impetus of powder gasses, compressed air, or other like means. A barrel may be rifled or smooth;
	Chamber – the rear part of the barrel bore that has been formed to accept a specific cartridge or shotshell. In a revolver the holes in the cylinder represent multiple chambers;
	Cylinder – the rotating part of a revolver, that contains the chambers;
	Frame – in revolvers, pistols, and break-open guns, the basic unit of a firearm which houses the firing and breech mechanism and to which the barrel and grips are attached;
	Body – another word for receiver or frame;
	Receiver – the basic unit of a firearm which houses the firing and breech mechanism and to which the barrel and stock are assembled;
	Breech block – the locking and cartridge head support mechanism of a firearm that does not operate in line with the axis of the bore;
	Bolt – on a rifle, this is a component which slides into an extension to the barrel at the breech end and rotates to lock.
	Subsection (5) inserts a new section 57A (exception for airsoft guns) into the 1968 Act. This provides that airsoft guns are not to be regarded as firearms, and defines what an airsoft gun is. It provides for slightly higher maximum permitted muzzle kinetic energy levels for airsoft guns: 1.3 joules for automatic variants and 2.5 joules for single shot variants. (These thresholds were informed by testing carried out by the (now disbanded) Forensic Science Service in 2011.)
	'Airsoft' is an activity employing low-powered air weapons in acting out military or law enforcement scenarios, where the participants shoot at each other with spherical plastic pellets of up to 8mm in diameter. The weapons in question are not rifled and are made from low density metal.
	Subsection (6) inserts a new section 57B into the 1968 Act which confers on the Secretary of State (in practice, the Home Secretary) a power to amend by regulations made by statutory instrument (subject to the affirmative procedure) the definition of relevant component part set out in the new section 57(1D).