Airsoft BBs Guide: Which Weight, Bio or Not, and How Many?

Airsoft BBs are 6 mm plastic balls. In Britain you will also hear BB gun pellets, but they have nothing in common with the lead pellets of an air rifle or the steel BBs of an air pistol. Never load those into an airsoft gun.

The barrel is only a fraction of a millimetre wider than the BB. One that is too big, out of round or carries a moulding seam jams or veers off, and one with an air bubble inside wobbles in flight. A poor bag saves you little. A jammed gun costs you a game.

Airsoft BB weight is a trade. A light BB leaves fast and is pushed around by wind and leaves. A heavy BB leaves slower and holds its line, but it needs enough power and a hop-up that can spin it. The table gives the weight to start with; your own gun has the last word.

A standard BB is ordinary plastic and stays where it falls. Bio BBs are made of a plastic that soil life can break down, usually PLA, which is made from plant starch. How fast that goes depends on the ground, the damp and the temperature, so we give no number of months.

Whether you need them is not your decision. It is a rule of the site and of the landowner behind it.

We do not rank brands: nobody has tested them all side by side, and your gun has an opinion of its own. What you can check is whether a maker states its tolerance and sells your weight in bio. In our webshop that includes G&G, Nimrod, Specna Arms and MadBull. On British sites you will also meet Nuprol's RZR line, which runs from 0.20 g to 0.36 g.

Tracer BBs glow in the dark for night games. They need a tracer unit, a small light at the muzzle that charges each BB as it leaves.

How many you use depends on your trigger finger. As a rule of thumb a rifle player gets through 1,000 to 2,000 BBs in a full day, a support gunner several times that, a sniper or pistol player a few hundred. One site we checked gives rental players 1,000 BBs per half-day. A speedloader, the hand pump that pushes BBs into a magazine, keeps them off the floor.

Keep BBs dry, closed and out of the sun. Unopened bottles sometimes turn up under BBs, gas and CO2 on the marketplace when a player quits: fine if the seal is intact, not if the bag has been open in a shed.

The chrono, short for chronograph, measures the speed of your BB before a game. Speed alone says little: the same shot is 350 FPS (feet per second) with a 0.20 g BB and 313 FPS with a 0.25 g one. Both are 1.14 joules, and energy is what a site limits. Limits used to be quoted as FPS with 0.20 g, which is why that weight is still the reference.

Joule creep is the catch. In most electric guns a heavier BB leaves with roughly the same energy. In gas guns, in HPA guns that run on compressed air from a bottle, and in electric guns built with a lot of air behind the barrel, a heavier BB stays in the barrel longer and leaves with more. A gun that passes on 0.20 g can be over the limit on 0.40 g.