AIRSOFT 101: RATE OF FIRE

Airsoft 101 : Rate of Fire

Many of us want fast shooting guns. Here are the mechanics of speed and options we have.

The rate of fire from an AEG is influenced by four things.

1. The gears used
2. The motor used
3. Voltage of the battery
4. The spring used
5. Special barrel issues

High speed gears, such as those made by systema, utilize tight tolerances and gear ratios to achieve a fast rate of fire. These gears make a distinct sound and increase the ROF quite a bit over stock parts. High-speed gears are vulnerable to stripping if used with strong batteries, a fast motor or a heavy spring.

*A lesser spring (lower FPS) will let high-speed parts work at an optimal level. Most gunsmiths suggest less than the 350fps range for Systema high speed gears.

An AEG’s motor has a direct impact on ROF. Motors come in a variety of strengths. For example Tokyo Marui guns can come with eg1000 eg750 or eg600. The Aftermarket company Systema sells a high-speed motor which will dramatically influence how many BBs are leaving the gun.

*Again if a heavy spring is used the resistance created endangers the gears and the gear thread on top of the motor, which can strip.

High-speed gears can be combined with a high-speed motor, but the risk is high. Gear stripping is a distinct possibility in this combination. A weaker spring and 8.4 battery are suggested for this set up.

A batteries’ voltage also contributes to ROF. The more voltage put to a motor the faster it will work. Some tests indicate that a 12volt battery with reinforced (not high-speed) gears actually gives the fastest possible/reliable ROF). 12v batteries can be large and may not fit in many guns. A common voltage is 9.6v.

The spring in an AEG primarily effects how hard the BB is propelled, shown in feet per Second (FPS). This effects rate of fire mainly through resistance. The stronger the spring, the more stress is applied to the gears and motor. High-speed parts are therefore put under even more stress through the action of shooting many BBs while overcoming the resistance of a heavy spring. The gun does not slow down its rate of fire, it simply strips gears when the system fails in overcoming the spring tension.

One of the best ways to think about this is a triangle of performance.

You have three options: speed of the BB, Rate of Fire, Durability.

You can only choose 2 of the three.

And remember, durability = $$$. If gears strip, chalk up $50+ to get the gun working again.

Special barrel issues are the mysterious ‘barrel suck’. Or the situation when a gun’s piston is working so fast it begin to draw air through the barrel instead of it’s normal intake. The effect is a dramatic loss of pressure, BB jamming, hop-up negation and general poor performance.

‘Barrel suck’ therefore does not only effect ROF but every performance aspect of the gun. The solution is either changing to a shorter barrel or upgrading the piston to a larger volume model. Please note this issue is seen only when dramatic changes are made to a gun, such as installing the super long PSG-1 barrel on a gun which uses a small version mech-box. It is not a common problem.