Chronographs

Chronographs are gauges that can be used to determine the speed of a flying ball in m/s or FPS, the impact energy in Joules or the cadence of an airsoft replica. Today's chronographs are often equipped with Bluetooth for communication with a mobile phone. Chrono is a very important tool for both airsoft fields and service centers. With the growing interest in HPA, they are also very popular among players themselves, for setting the optimal performance of the replica.

There are various types of chronographs on the market today. Some models boast a color display, or have integrated batteries, or can be paired with a phone via bluetooth to store measurements and other data. Most models sold today have the ability to automatically turn off after a certain amount of inactivity which saves battery, for example when taking a quick measurement before an event and then forgetting the chrono in the car.

A very useful feature of most models is the ability to screw the chronograph onto the camera tripod. This makes handling the weapon easier and increases the quality of the measurement by a bit, this will be appreciated especially by service centers, game organizers or home technicians.

HOW IS THE CHRONO USED AND HOW TO MEASURE CORRECTLY?

The measurement is made in m/s, but more reliable is the measurement in J.
Very important for an objective measurement of performance is to measure with the weight of the balls the player is using. Previously, measurements were made with 0.2g ammunition, which used to be problematic. Today, the most common ammunition weight used is 0.28 or 0.30g, and for snipers it is 0.45 or more.

It is very important for measurement that the gun is horizontal to the chronograph and, often forgotten (sometimes deliberately), the hop up is turned off, where the real performance of the gun can then be reduced by throttling the hop up.

WHAT IS THE DIFFERENCE BETWEEN J AND FPS WHEN MEASURING AND WHAT IS RPS?

Nowadays we can see double limit at events. Some venues require power in m/s or FPS, other venues, especially CQB arenas, require "J" for safety in close combat. All of these quantities describe impact energy. But what is the difference between them?

RPS

RPS is a quantity for cadence, or it tells us how many pellets the gun fires per second.

FPS

FPS stands for feet per second, and in airsoft it indicates the speed at which a bullet moves forward after being fired from an airsoft gun. In foreign countries, this is a very common quantity in which airsoft guns are measured. In our country, the measurement in meters per second is more commonly used.

M/S

Just like FPS, m/s is the magnitude of the speed of flight of a bullet. For both units, it is important to measure with the weight of the balls that are most often used in play or by the player themselves. This allows us to measure the airsoft gun as accurately as possible.

Joule

The airsoft community has gradually established a new standard - limits based on joules. Joules (J) represent a unit of kinetic energy, a scientific way of measuring the force exerted by a moving object. Simply put, it indicates how much "force" the ball has behind it. Here's the key difference: joules take into account both the speed of the ball and its mass. This creates a more comprehensive picture of the force of the gun, which leads to several advantages:

Standardization and fair field conditions: unlike FPS, which can vary slightly depending on conversion processes, joules provide a universal measure of energy. This style of measurement provides us with the same game limits for everyone.

Increased player safety: by taking into account both the weight and speed of the balls, the limits in joules allow for a more comprehensive approach to safety. This minimises the risk of injury, especially to players in close proximity - typically CQB . Each pitch sets its own maximum limits, this limit is then required of players. Sometimes these are universal values for all players, but in most cases the limits are set by weapon type. Pistols and SMGs typically have low limits, while sniper rifles usually have the highest limits. Setting these stretch limits on our courses will ensure a safe, enjoyable and most importantly fair experience for all players.

Calculating the joules of your replica

Want to make sure your airsoft gun meets the safety limits of the range?
The easiest and most accurate way is to use a chrono, the vast majority of chronos on the market can also convert the measured power into Joules.
If you don't own a chrono yet, but you know what power your replica has, just enter the weight of the ammunition you are using and the muzzle velocity of the gun into specialized applications, or you can use our conversion table below.
This will give you an idea of not only the performance of your gun at different ammo weights, but more importantly if you will meet the course limits at that ammo weight.

FPS TO J CONVERSION TABLE

Today's chronographs such as ace tech commonly measure power in both M/S and FPS, but they can also convert the values to Joules. This will be especially appreciated by HPA players who visit different courses with different power outputs.

During the measurement we have to pay attention to the phenomenon called Joule creep.

Chronograph in the silencer: Some illuminating silencers, for example from Acetech, have a ball speed measurement mode in certain models in addition to the illumination function of the tracer BBs. The measured values are then transmitted via bluetooth to the mobile phone.

JOULE CREEP AND WHY IT CAN BE DANGEROUS?

Joule creep is a phenomenon that commonly occurs in airsoft and affects the "performance" of an airsoft gun. It's a major issue that can cause your airsoft gun to be too powerful when measured to use on the field.

When we measure a weapon's energy of pull, we tend (especially from the past) to measure using 0.2g BB. This is mainly because fields usually have cheap 0.2g BB available, which can be problematic.

As an example, consider the sniper rifle, where joule creep is most commonly encountered and often targeted.

A player with a sniper rifle fires 0.20g BB ammo through the organizer's chrono instead of his significantly heavier BBs that he normally uses during the game. The muzzle velocity is recorded for the example as 150 m/s at 0.20 BBs which would equate to - 2.25 joules using 0.2g BB.

As the course has set sniper rifle limits of 150 m/s or 2.3 J - the organiser is satisfied that the rifle is OK within the limits.

However, snipers do not use 0.2g BBs in their rifles. For greater accuracy and range they use heavier weights, as we wrote above. So if a player chooses to use a heavier ball, e.g. 0.4g, which they 100% do - the same sniper rifle could now ultimately shoot with an energy of around 3.6 joules (i.e. 1.3 joules higher) in certain cases, even though the spring force (or HPA pressure, etc.) has not changed. Only the weight of the ammunition has changed.

This phenomenon is called joule creep: a physical change in the rifle's output energy directly dependent on the weight of the bullet.

What causes joule creep?
When a bullet weighing 0.2 g is shot through the barrel, it is pushed by the compressed volume of air until the bullet leaves the barrel and can no longer accelerate.

When a heavy bullet is fired, it is also pushed by a compressed volume of air, but takes longer to leave the barrel (because it is moving at a lower velocity). If there is enough air behind the bullet, it will continue to accelerate, giving it more energy than lower weight bullets.

This is caused by "excess air volume", where more air is used to propel a light bullet than is needed, and by the time a heavier bullet is fired, it has more time to use this excess air volume, resulting in a higher muzzle velocity.

The end result is a weapon that shoots within limits when using 0.2g BB, but when the player uses a higher weight, it shoots at a higher muzzle velocity. In rare cases, this phenomenon is actively abused by some players.

Dangers of Joule Creep
This phenomenon makes it very easy to have, for example, a CQB situation where less power is better than more power, then the likelihood of injury increases due to the high power of the weapon. This is why pitches often take random measurements during the event to detect a potential cheater in action and prevent him from playing again early.

TIP: We therefore recommend that you remeasure your weapon with the weight of the pellets you intend to use in the weapon. This will help you determine if your weapon is accidentally violating the rules of the course.