How to Chrono an Airsoft Gun: A Beginners Guide

Whats an Airsoft chronograph used for?

An Airsoft Chronograph is a bit of airsoft kit, that lets you can test how hard and powerful your airsoft gun is shooting, which you need to do when you go to an airsoft match to make sure your bb gun/airsoft is not firing too hot so that you don't hurt anyone when firing at them.

You can test your gun in feet per Second (FPS) or Joules (J); when testing in joules, you will enter the weight of your bb pellet into the Crono, and when you fire the BB it will record the FPS and the take in to account the speed that it's going and this will give you the joules/energy reading

For example, An airsoft gun firing a .020g BB Pellets at 350 FPS is 1.14J of energy.

Its best to check your gun before you go to an airsoft game site, but if you can't, most or all sites will check your gun before they let you play on the field.  

here we are going to attempt you give you the lowdown on how to test your bb gun, and what else you need to consider when having a fun day out airsofting.

Basic Settings on an Airsoft Chronograph

Here are some of the settings you will see and use on a Chronograph.

FPS
the most used and looked at will be your FPS Clock
(FPS) or Feet per Second is how Powerful your bb gun is shooting.

For example, if your bb gun is firing at 350 fps, this means the bb pellet will travel 350 feet in one second.

RPS
Less well used but still useful is the "RPS" clock
Or Rounds per Second this shows you How many rounds your bb gun is shooting in one second

so when you test your airsoft/bb gun on full auto, if the Crono is saying "12", this means your gun is shooting 12 rounds per Second when your trigger is fully pulled for one sec (Some airsoft chronographs can alsos measure in rounds per minute (RPM))

Joules
The Joules (J ) is How much energy your shot has.
A Joule is a unit of energy, A 0.20g bb moving at 350 feet per Second will be 1.14j but a 0.30 bb pellet moving at the same speed will be 1.71j (see the chart below for more details.

For comparison, the kinetic energy of a 1kg apple falling 1 meter to the ground is approximately 9.8 joules.

I think Probably the best and most accurate way to test the power of an airsoft gun is to calculate its power in joules, then there is no arguments and it will be safer for you and other players.

Using Different-weight airsoft pellets

The FPS speed will change a lot depending on the weight bb pellet you use.

The lighter the bb pellet, the faster it will go, and the heavier, the slower but more heavy bb pellets will be less affected by wind but will drop off a bit quicker, affecting the bb guns working range.

How to Chrono an Airsoft Gun

Step-by-step Setup Guide

Safety first, always wear some eye protection like some airsoft goggles when shooting an airsoft gun. 

1. Set up your Chrono testing area; you need to have a safe area space with no people or animals, or property behind it. If you're not doing this in an outdoor open space, you need to have a stop behind the Crono that will catch the BBs fires through it. If not, when you hit a hard surface, an airsoft bb can come back with enough force to hurt people or damage things.
2. Set up the airsoft Chronograph: Place the Chronograph in front of the airsoft gun's muzzle, making sure that the shot-through tube is properly aligned with the barrel
3. Fire a few test shots through the Chronograph (6 to 7) to ensure that everything is lined up correctly and to get an initial reading of the BB's velocity; shooting at an angle can cause a bad reading.
4. Next Record, the velocity of each BB pellet as it passes through the Chronograph shot. Several BB pellets are used to ensure an accurate average velocity is recorded. (the hardest recorded shot is the one used.)
5. If the velocity is too high, adjust the gun's hop-up or spring tension.
6. Repeat the Chrono testing process until the gun's velocity is within the allowed limit for the airsoft game site.

It's worth noting due to the way a chronograph works, it is possible to get false readings, and a bit of testing is needed.

If not shooting straight, the bb may hit the inside of the Chronograph, not registering correctly, read slowly and may even break the Chronograph sensors.

Outdoor Airsoft Skirmish site Limits

At an outdoor airsoft game site, the FPS Limit will normally be higher; in the UK, the standard FPS for an airsoft rifle on its full auto setting, snipers rifles and semi-auto locked "DMRs" will be a bit higher fps and probably around the 500 fps mark.   

Usually, some other restrictions may apply; for example, restricting your MED (Minimum Engagement Distance or how close you can shoot from) 

The rate of fire could also apply to keep the game fair and, importantly, safe; if your airsoft gun is firing too fast, if you put a lower voltage battery in it, this will lower your gun's rate of fire. 

If a game site has outdoor and indoor aspects, players can be required to carry a "zero MED" secondary weapon for close range and room clearing alongside their primary weapon. 

Indoor or CQB FPS Limits

Indoor or CQB (Close Quarter Battle) arenas can have players shooting at each other from very close range; sometimes, it can even be point-blank. Airsoft Players are typically restricted to only using semi-auto pistols, with an fps limit of approximately 300 using 0.20 BBs, and semi-auto is mostly the only firing mode allowed. 

It's possible that some game sites have higher or lower limits, while others might let you use full auto under specific circumstances.

Keep in mind some times there is no opportunity for long-range combat in some indoor arenas, and the action takes place at a very close range. In these kinds of predicaments, a hi-powered weapon like a long rifle could be more trouble than it's worth.

Using an Airsoft Jules chart

Using a Chrono Chart, match feet per Second to bb weight. This is your joules rating.

Using this chart, you can compare the energy by weight of a bb pellet.

For example, a sniper rifle firing a heavy .45g BB at 260 FPS is 1.41J. The almost the same energy as a 0.25BB fired at 350fps! 

This shows why FPS alone is not an accurate judge of a bb pellets power.

Due to the way a chronograph works, it is possible to get false readings. 

False Readings from Gas Airsoft guns

Airsoft Gas or CO2 ejected from the barrel of a gas blowback pistol on the shooting can sometimes be detected and measured by the Chronograph. This can sometimes make the feet per second reading in the thousands of fps, but this will be obvious when it happens.

Inefficient blowback systems, freshly filled gas magazines, newly inserted c02 cartridges, or even hot magazines can also cause this issue. 

Watch for excess gas leaving the end of the barrel on firing.

You may have to move back a few inches from the hole. Be careful not to hit the Chrono or shoot at an incorrect angle.

Recording Airsoft Shotguns

Multi-bb shotguns fire three or more BBs per trigger pull, which makes them very hard to get a good reading and also to get the bb pellets to actually go into the Chronograph; erratic readings are the norm with this type of shotgun, but 99.9 per cent of this type of shotgun will fire below 350 FPS, But check with the manufacturer or retailer to be sure.

BB Gun shotgun models that fire one bb at a time can be easily tested and will not be a problem to test 

Can you Cheat to Pass Chrono test ? 

When you go to a site you will be asked what weight pellets are in your gun, or they may give you a few pellets for you to use for the test. it's best to tell the truth because if you lie and they catch you out, it could lead to a ban, and it's not very sporting anyway, so stick to the truth 

1. Safety: cheating in a chrono test and having airsoft guns shoot at higher power than allowed which can be dangerous for players and could damage other players' equipment.
2. Fairness: Cheating a chrono test gives an unfair advantage to players with a higher FPS
3. Legal Consequences: Modifying an airsoft gun to shoot at higher power can even be illegal in some places.
4. Your Reputation: Cheating on a chrono test can also damage your reputation, both within the airsoft community.
5. it could get you banned from the field or future games.

It is always best to play fair and to follow the rules and regulations as they have been made for a reason.

also see the video below.

So there we have it. An airsoft Chronograph is used to check if your bb gun is safe to use at an airsoft game site, Simple as that!