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What Is a BB Gun? Airsoft vs Steel BB Guns

In the UK, 'BB gun' means two things: an airsoft gun firing 6 mm plastic BBs, or an air gun firing steel BBs. How they differ, and what the law says about each.

6mm vs 4.5mm: Plastic or steel BBs: two different guns in law
Callum Robley
  • Published
  • 10 min read

In the UK, "BB gun" means two different things. Most often it refers to an airsoft gun that fires 6 mm plastic BBs - the sense the police and Scottish Government use. It can also mean an air gun that fires 4.5 mm steel BBs, which the law treats as an air weapon. They look similar, but different law covers each.

This guide explains what each type is, how the law classifies it, who can buy one, and what the rules say about carrying either in public. It is not legal advice.

Two guns, one name

Ask the Police describes BB guns as guns that "fire plastic or aluminium balls ... by different methods such as compressed air or an electrical system." The Scottish Government's guidance says "BB guns are generally designed to fire low energy plastic pellets." Both sources use the term for the plastic, airsoft-type gun.

In peer-reviewed research the term means something different. Scientists use "BB" for the 4.5 mm (.177) steel ball - what Kamphausen et al. (2019) call a "BB (ball bearing)." Joseph and Meredith (2000) describe it as "spherical diameter of 4.5 mm and a copper plate covering a steel core." So the police and gov.scot both use "BB gun" for the plastic-BB kind, while medical papers use it for 4.5 mm steel balls.

That split matters here. An airsoft gun and a steel BB gun can look almost identical. They sit in different legal categories and fire different ammunition.

Airsoft guns: plastic BBs

Section 57A of the Firearms Act 1968, inserted by the Policing and Crime Act 2017, says an airsoft gun is not a firearm for the purposes of that Act. Two tests decide whether a gun qualifies: it must be designed to fire only a small plastic missile (plastic, spherical, and no more than 8 mm across), and it must not be capable of firing above 1.3 joules if it fires more than one shot per trigger pull, or 2.5 joules otherwise. This applies in England, Wales and Scotland.

The typical airsoft BB is 6 mm plastic (Marshall et al., 2011). Our guide to FPS and joule limits explains the power levels used at sites.

Airsoft is played at organised sites, most of which check guns before play. Our introduction to airsoft covers how the game works.

Steel BB guns: air weapons

A gun designed to fire 4.5 mm steel BBs does not meet section 57A's plastic-only requirement. It falls under the air weapon rules in the Firearms Act 1968 instead.

Section 57(1B) defines a "lethal barrelled weapon" as one that can fire a missile with kinetic energy of more than one joule at the muzzle. Section 1(3)(b) defines an "air weapon" as an air rifle, air gun or air pistol that is not prohibited and not specially dangerous. A steel BB gun over 1 J is therefore a firearm and an air weapon, but it does not need a firearm certificate unless it crosses the "specially dangerous" threshold.

The Firearms (Dangerous Air Weapons) Rules 1969 - with separate versions for England and Wales (SI 1969/47) and Scotland (SI 1969/270), each amended in 1993 - declare a gun specially dangerous if its muzzle energy exceeds 6 ft lb for an air pistol, or 12 ft lb for any other type, or if it is disguised as another object. The Scottish Government's guidance gives those thresholds as 8.13 joules and 16.27 joules. An air pistol over 6 ft lb is not merely certificate-only - the Home Office Guide (paragraph 2.46) states it is a prohibited firearm.

The difference at a glance

Airsoft gunSteel BB gun
What it firesPlastic BBs, typically 6 mmSteel BBs, 4.5 mm
Legal class in GBNot a firearm if within limits (s.57A, 1968 Act)Firearm and air weapon if over 1 J (s.57(1B), s.1(3)(b))
Power limit in law1.3 J full-auto / 2.5 J otherwiseSpecially dangerous above 6 ft lb (pistol) or 12 ft lb (other)
Buying age18 (imitation firearm, s.24A)18 (s.22(1), s.24(1))
ScotlandQualifying airsoft guns excluded from air weapon certificate schemeAir weapon certificate needed if over 1 J (2015 Act s.2)
Northern IrelandNo airsoft exception; 1 J threshold applies (Order Sch. 1 para 9)1 J threshold applies (Order Sch. 1 para 9)

Who can buy one

Airsoft guns are imitation firearms. Section 24A of the Firearms Act 1968 makes it an offence for anyone under 18 to buy an imitation firearm, and an offence to sell one to them. Selling a realistic imitation firearm (RIF) is an offence unless the seller has a defence, such as the gun being for skirmishing. Our UKARA guide explains how retailers check that a buyer skirmishes, and our guide to airsoft law in the UK covers the RIF rules in full.

Steel BB air weapons in England and Wales carry similar age rules. Section 22(1) of the 1968 Act makes it an offence for anyone under 18 to buy or hire a firearm or ammunition. Section 24(1) makes it an offence to sell or let one on hire to an under-18. An under-18 who has one with them commits an offence under section 22(4), unless supervised by someone 21 or over, at an approved shooting club or gallery, or - for those aged 14 or over - on private premises with the occupier's consent (section 23). Section 24ZA, added by the Crime and Security Act 2010, makes it a separate offence to fail to take reasonable precautions to prevent an under-18 from accessing an air weapon.

Sales of air weapons by way of trade must go through a registered firearms dealer and be handed over in person - Violent Crime Reduction Act 2006, sections 31 and 32, in effect in England and Wales.

Scotland

The Air Weapons and Licensing (Scotland) Act 2015 requires anyone in Scotland who uses, possesses, buys or acquires an air weapon to hold an air weapon certificate. Qualifying airsoft guns are excluded, as the Act (section 1(4)) and the Scottish Government's guidance both confirm. Section 3 of the Act allows anyone aged 14 or over to apply for a certificate.

Northern Ireland

Northern Ireland has no airsoft exception equivalent to section 57A. The Firearms (Northern Ireland) Order 2004, Schedule 1, paragraph 9 allows a person to have an air gun without a firearm certificate if it cannot fire above one joule - far below the "specially dangerous" level in Great Britain. Under-18s face additional limits under paragraph 9(3). Schedule 1, paragraph 8 provides a separate exemption at a licensed recreational facility running combat games, but it does not apply to anyone under 16. The RIF rules in the Violent Crime Reduction Act 2006 apply in Northern Ireland via Schedule 2 to that Act. Before buying, using or carrying either kind of BB gun in Northern Ireland, check with the PSNI.

"Kids'" and toy BB guns

Spring pistols that fire plastic BBs - often clear or brightly coloured, sometimes marketed as toy BB guns or children's BB guns - are not automatically excluded from the under-18 buying rule.

Section 24A of the 1968 Act applies to anything that "has the appearance of being a firearm", whatever its colour. Article 66A of the Firearms (Northern Ireland) Order 2004 applies the same test in Northern Ireland. The Home Office Guide (paragraph 7.36) is direct on this: the under-18 rule "will also apply to non-realistic imitations which nevertheless have 'the appearance of being a firearm'. This could include some children's toys." The Guide adds that whether a specific item falls within the definition is "ultimately ... for the courts to decide."

The colour rule affects adult sales, not the under-18 rule. An imitation firearm whose principal colour is bright red, orange, yellow, green, pink, purple or blue - or which is made of transparent material - is not a "realistic imitation firearm" under section 38(3) of the Violent Crime Reduction Act 2006 and the 2007 Regulations. That means the section 36 sale ban, which requires a statutory defence, does not apply to it. Section 24A's under-18 restriction is a separate provision. It runs on appearance alone, regardless of colour. A plastic BB gun that looks like a firearm is still caught by it.

Staffordshire County Council lists BB guns as age-restricted to 18 and runs test purchases. Ask the Police says: "it is not advisable to allow young children to be in possession of them."

A spring pistol designed to fire only plastic BBs within section 57A's limits is not a firearm under the 1968 Act. That does not affect section 24A, and section 19 still applies to it in a public place - that is covered in the next section.

Our guide on how old you have to be to play airsoft covers minimum ages at sites separately.

Can a BB go through skin?

Steel BBs can break skin and go deeper. Kiwanuka et al. (2018) describe air-powered rifles that "shoot ball bearings with enough kinetic energy to penetrate skin and fracture underlying bones." Case reports include a steel BB travelling through the cheek and lodging in the sinuses (Chhetri and Shapiro, 2004). One 1990 US paper (Ford, Senac and McGrath) cites earlier work putting the speed needed to break skin at 150 ft/sec; it doesn't say which projectile.

Plastic airsoft BBs are recorded seriously injuring eyes. Gupta et al. (2018) report a 12-year-old suffering corneal perforation, cataract and an intraocular foreign body after being struck by an airsoft BB. Strong and Coady (2014) noted "no reports of penetrating injuries to other areas of the body" before presenting a UK case of an airsoft BB penetrating the cheek. There is no frequency data for skin injuries from plastic BBs. No source supports the claim that airsoft is safe, or safer than steel BBs, as a general statement - so we do not make one.

Our article on whether airsoft hurts covers eye injuries and protection standards.

In public, both are treated as real

Section 19 of the Firearms Act 1968 makes it an offence to have an air weapon or an imitation firearm in a public place without lawful authority or reasonable excuse. This covers a steel BB gun as an air weapon and an airsoft gun as an imitation firearm, whatever its power level. Section 19 applies in England, Wales and Scotland. In Northern Ireland, Article 61 of the Firearms (Northern Ireland) Order 2004 makes it an offence to have an air gun (whether loaded or not) or an imitation firearm in a public place without lawful authority or reasonable excuse.

Ask the Police puts it plainly: "Possession of a BB gun that looks like a real firearm in a public place will amount to an offence of possession of an imitation firearm, regardless of the power of the gun itself."

Ask the Police also warns that "many BB guns are extremely realistic and the police treat all reports involving weapons as if they are real live firearms." Our guide on where you can use an airsoft gun covers public places, transit to a site and private land in detail.

Find a site near you

Airsoft is played on organised sites. Airsoft Fields checks its listings against the UKARA and BAC registers every week. Search by postcode or town to find a field near you, or browse fields by city.

Sources.

Published 22 Oct 2026.

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