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Mexar Airsoft

Calculators

Joules, rate of fire and air ratio, worked out as you type. Pick where you play to see the limits that apply.

Every site sets its own limits and its own rules win on the day. These figures help you get close; the site's chrono has the final say.

Where you play

Power

1.14 JMuzzle energy
350FPS on 0.20g
106.7Metres per second

Typical site limits

CQB330 FPS1.01 J on 0.20gNo MEDIndoor and close-quarters sites. Some allow 350, a few only 300.Over by 0.13 J
AEG or rifle, outdoor350 FPS1.14 J on 0.20gNo MEDPistols the same.Under
DMR450 FPS1.88 J on 0.20gMED 20mSemi-auto only, with a sidearm for inside the MED. Some sites cap DMRs at 400 to 425.Under
Bolt-action sniper500 FPS2.32 J on 0.20gMED 30mOne shot per cycle, with a sidearm for inside the MED.Under

Typical UK site figures, not a national standard. Every site sets its own limits, so check with the site before you go. MED means minimum engagement distance: you may not shoot anyone closer than that. Sources: Firearms Act 1968, s57A (legal limits); Red Alert Paintball, Reading: airsoft site rules; Patrol Base: power and FPS limits explained; Platoon Stores: airsoft FPS limits UK. UKARA is the register shops check and sets no power limit.

Energy (J) = ½ × BB mass (kg) × speed (m/s)²

United Kingdom: against the law

1.3 JLegal limit, full-auto-capableUnder
2.5 JLegal limit, single shotUnder

The law in United Kingdom

  • An airsoft gun stays outside firearms law while its muzzle energy is no more than 1.3 J for a gun that can fire on full auto, or 2.5 J for any other airsoft gun, and it fires plastic BBs of 8mm or less (Firearms Act 1968, section 57A). This covers England, Wales and Scotland.
  • Selling, importing or making a realistic imitation firearm is an offence unless a defence applies, such as buying it to play airsoft at a site that holds public liability insurance (Violent Crime Reduction Act 2006, sections 36 and 37, and the 2007 Regulations). That is why a shop asks for proof that you play.
  • Without that defence a shop can only sell you an imitation whose main colour is bright red, orange, yellow, green, pink, purple or blue, or which is see-through (Violent Crime Reduction Act 2006, section 38, and the 2007 Regulations).
  • You must be 18 to buy an imitation firearm. Selling one to anyone under 18 is an offence, and so is buying one when under 18 (Firearms Act 1968, section 24A).
  • Having an imitation firearm in a public place without a reasonable excuse is an offence. Carry it to and from a game covered, in a bag or case (Firearms Act 1968, section 19).

This is a plain summary, not legal advice. Laws change, so check before you buy, travel or play.

Rate of fire

6.0 sTo empty the mag

RPM = RPS × 60 · time to empty = rounds ÷ RPS

Some sites cap the rate of fire as well as the power.

Air ratio

2.81Air ratio
Suits heavy BBsRough guide

Ratio = π × (cylinder bore ÷ 2)² × (cylinder length − head) ÷ (π × (barrel bore ÷ 2)² × barrel length)

It compares the air the cylinder pushes with the space in the barrel. A ported cylinder only uses the air behind its port, so measure from there. The bands are a starting point for tuning, not a rule.