How Airsoft BBs can affect the performance and functionality of your Airsoft gun.


Optimal BB weight for your Airsoft guns.
300-350 FPS: .20G
350-400 FPS: .25G
400-450 FPS: .28G
450-500 FPS: .36G
500 FPS: .43G

BBs are an inexpensive investment for your Airsoft guns. But bear in mind, buying low cost Airsoft BBs such as the kind you see sitting on the shelves from various sporting goods stores will not only cause damage to the gearbox components and might burn a hole in your wallet from costly repairs in the long run.
So you might ask yourself, so why are they so cheap then? Well it’s because they’re meant to be used with low quality Airsoft guns. If you had the chance of running into these type BBs, you’ll notice their size, shape and weight are completely off. Some of them are not even spherical.

What will happen if you use these low grade BBs?
  • BBs are not spherical thus causing jam or get stuck in the barrel (Fig 5)
  • Materially imperfect causing them to break into pieces in the barrel, again causing a jam (Fig. 8)
  • BBs are not sized properly for 6mm barrel and reduce velocity (Fig. 6)
BB jammed in the barrel in some cases are not as simple as un-jamming them. Let’s explore the following scenarios:
  • BBs are not spherical thus causing jam or stuck in the barrel (Fig 5)
The operator didn’t notice the jam and continues to pull the trigger allowing MORE BBs in enter chamber. The chamber and inner barrel is now jammed full of BBs blocking the passage for the “air” gathered by the retracting piston and cylinder to push the BBs out of barrel unable escape thus creating an “air brake”. In consequence, this causes the piston to only travel half way because the “air brake” is restricting the path of the piston. With the stopped piston, the gears continue to spin and strip the teeth on the piston as well as the gears itself (just imagine all the moving components in the gearbox are now rotating backwards). Can you imagine a gush of air capable of propelling BBs 350 feet per second is now going back INTO the gearbox?
  • Materially imperfect causing them to break into pieces in the barrel, again causing a jam (Fig. 8)
It’s well known for low grade BBs to break into pieces in the barrel. For example, the first BB gets stuck in the barrel, the following BBs are hitting the first stuck BB in the barrel shattering into little tiny pieces. The broken pieces of the BBs manage to travel BACK into the gearbox causing catastrophic damage to tightly fitted gears, piston, cylinder, breaking the tappet plate just to name a few.
  • BBs are not sized properly for 6mm barrel and reduce velocity (See Fig. 6)
Most of these Airsoft BBs guns are equipped with tightbore 6mm inner barrels. Improperly sized BBs will not travel as far because these types of BBs are not a “tight fit” with the barrel by allow air to escape around the BBs within the barrel instead of trapping the air behind the BB allowing it to push the BBs harder out of the barrel. BBs made in China should be avoided. Always buy from Taiwanese or Japanese manufacturered brands.
Buying cheap BBs are like putting 87 octane gas in a car requiring 92 octane to run properly. So do yourself and your Airsoft guns a favor, use .20g or higher Airsoft BBs such as the ones on and you’ll thank yourself later on down the road.
Happy Airsofting!

Brightly colored BBs are a very good indicator of low weight, and often low-quality BBs. These BBs are often very light and brittle. Often times, they have many major imperfections including nubs, lines, dimples, burrs and cracks. An easy way of distinguishing low quality BBs is where it was made. BBs made in China are usually poor in quality while BBs made in Taiwan and Japan are of much better quality.

Fig. 2
Clear or transparent BBS are often found at various sporting goods and general stores such as KMart, Walmart and Big 5. The are often times falsely mislabeled as "high precision" or "high quality" BBs. On the contrary, these BBs are extremely low quality. They often have air bubbles, which cause them to be off-balance, which can cause them to tumble in flight. They also exhibit the same poor qualities as the brightly colored BBs.

Fig. 3
When you purchase an airsoft gun, often times it will have 100 or so rounds included. Although they are included with the gun, they are usually very low quality and can damage your brand new gun. Use of these included BBs are NOT covered under warranty.

Fig. 4
Never reuse BBs that have been shot, or have been dropped in the dirt. Dirty BBs will cause jams inside barrels and can cause a catastrophic failure of the gun's gearbox or firing mechanism.

Fig. 5
Never load or use malformed or deformed BBs. These types of BBs can be found even in high quality bags of BBs. They often are extremely malformed to the point that they no longer resemble a BB. Be careful when loading high-capacity magazines as they can often slip past unnoticed. Use of these BBs can damage the magazine, or worse, the gun itself.

Fig. 6
Using properly sized BBs is an extremely important factor. For one, it affects velocity. When using a BB of the correct diameter, it ensures that most of the air remains behind the BB. This allows the pressurized air to push the BB through the barrel using most of the air.

Using poorly sized BBs can cause loss of velocity. BBs with out of spec diameters can allow air to travel past, and around it. This means that the potential of the air escaping is lost. There is not as much air behind the BB, causing it to lose velocity.

Fig. 7
Use of properly sized BBs can also affect overall accuracy and range. Having a tight fitting BB inside a barrel ensures that the BB is not bouncing around inside the barrel, allowing it to maintain its proper trajectory after leaving the barrel.

When BBs are too small, they can become very inaccurate. Similar to the Muskets used during the mid 1700's, a projectile that is significantly undersized in comparison to the bore will allow the projectile to move freely in all directions while exiting the muzzle. This means that the projectile can bounce around inside the bore with minimal guidance, thus being extremely innacurate.

Fig. 8
Using poor quality BBs can cause the BBs to jam in the barrel and can cause some of the BBs to shatter. These tiny fragments of plastic are small, and may get into the internal workings of the gun, causing malfunctions.

Fig. 9
Often times, when a gun is jammed due to bad BBs, the problem transfers all the way into the gearbox. Even the durable metal teeth of the gears can be permanently damaged from use of poor BBs.