Richard Saunders puts his picks through their paces

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Why chronographs for airguns are key

Ignorance, it is said, is no defence in law. Responsible airgunners know that without a Firearm Certificate (FAC), possessing a rifle that pushes out more than 12 foot pounds (ft-lb) will not only get you into trouble, but fuel the argument of those who’d like to see our sport disappear.

There really is no excuse for exceeding the legal power limit and that’s where chronographs for airguns are useful kit.  Manufacturers go to extraordinary lengths to ensure their products comply, and licensed gunsmiths know that any breach would have serious consequences for their livelihood.

However, the reality is that even new guns can see power levels creep up over time. Personally speaking, everything I touch with a spanner explodes in a cloud of springs and cogs and can only be fixed with the skilful application of a credit card.

However, many of us like to tinker with our rifles – springer owners love nothing more than fitting tuning kits, and I’ve lost count of people who’ve told me about the ‘mods’ they have made to their PCP air rifles.

Fortunately chronographs for airguns will help you stay on the right side of the law. They also have many more uses beyond keeping you legal.

For example, a ‘chrony’ will determine the sweet spot on your PCP – the fill pressure range where your rifle is most consistent. It will also help you identify potential problems, and for you tinkerers out there, it will validate the effectiveness, or otherwise, of your labours.

How they work

Crudely put, chronographs measure the time it takes for a pellet fired from a gun to pass between two sensors. To work out the energy output, the feet per second (fps) reading has to be multiplied by itself, then multiplied by the weight in grains of the pellet and divided by 450,240.

So, let’s say your .22 rifle gives a reading of 530 fps. With 16 grain pellets, that would be: (530 x 530 x 16) / 450,240 = 9.98 ft-lb. Fortunately, if maths isn’t your thing, plenty of calculators on the internet will do the number-crunching for you.

We’re putting four different chronographs for airguns ranging from £49.50 to £265 on the test bench.

1. Combro CB-625 MK4 £15

Best for specific airgun use

Spec:

  • Weighs 55g
  • Measures 150x49x23mm
  • Handles maximum output of 2,000+ per second
  • Four Duracell LR44 batteries supplied

+ Small and compact
+ Designed specifically for airgun use
+ Good instruction manual
+ Safe to use anywhere

The  Combro cb-625 mk4 is a competent and effective tool. The unit is designed specifically for airgun use, while claiming (a little confusingly) to handle a maximum of 2,000+ feet per second.

It attaches to the muzzle with a couple of elastic bands, and uses a yellow plastic tool to ensure alignment with the bore. You can also use the cb-625 on guns with silencers. Each cb-625 comes with a specific reference number which you can use to access the test data on Combro’s website.

Airgun Shooter Verdict: “While the light weight is the cb-625’s strength, it is also its weakness. You have to make sure it is properly set up. Even a slight misalignment will result in a pellet smashing into it, although spares are cheap and readily available. And unlike the other products, checking the readings means having to look towards the dangerous end of your gun, so remember – safety first. That said, it’s easy to use and does everything the bigger and more expensive products do.”

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2. AirForceOne Ballistically Brilliant Chronograph £106

Best for quality

Spec:

  • Weighs 320g
  • Measures 105x70x57
  • Comes with data lead

+ Quality engineering
+ Light aluminium casing
+ Free software to download can analyse results

– Doesn’t automatically calculate power levels

You’ll instantly appreciate the quality of the  engineering. It’s compact and light enough to go into a rucksack, thanks to its aluminium casing.

The unit comes with a lead to transfer information via a data port to a computer, and a charging cable which also attaches to a PC. The Shooting Party recommends the Ballistically Brilliant Chronograph be fully charged before use, and says it can handle velocities up to 2,789 fps.

There is no facility to enter the weight of your pellet and calculate power levels automatically. However, you can download free software to do the maths for you, and by plugging in the supplied data cable, you can also record and analyse the results.

Airgun Shooter Verdict: There’s no denying the quality of the AirForceOne Ballistically Brilliant Chronograph – it will serve you well, and is tough enough to handle a few misplaced shots without any series mishap. It covers all the basics and plenty more once you have downloaded the software.

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3. SKAN Chrono PRO1, Series 3, DIAMOND 40th ANNIVERSARY Latest Model £229.99

Best for serious use

Spec:

  • Weighs 1.2kg
  • Measures 213x120x160mm
  • Provides fps and ft-lb energy reading
  • Five year warranty

+ Customers include many airgun manufacturers
+ Professional feel
+ Designed specifically for air rifles
+ Very durable

– Batteries not included
– No data port

If you take testing your air rifles seriously, you’ll really want to take a look at this chrono which is the last in our list of chronographs for airguns. According to Skan, police forces use a version of the product here to test potentially errant air rifles and pistols. Many airgun manufacturers are customers too.

It’s a precision instrument better suited to setting up indoors on a bench with a proper backstop, as opposed to use in the field.

Although it will handle projectiles weighing up to 49.9 grains and 4,000 fps, the Skan is designed purely for air rifles. Don’t be tempted to use it on your powder burners, as it will damage the sensors.

With four buttons, the Skan is simple and intuitive to operate. You can enter the weight of the pellets you are using, and the unit will not only provide a reading in fps, but it will provide an energy reading in ft-lb.

It will also store 50 shots and retain the data after the unit has been switched off. There’s no ability to port data to a computer, although it’s possible with an upgraded model for £339.

Airgun Shooter Verdict: The Skan Pro 1 Series 3 Diamond Chroni 40th Anniversary Model is a serious piece of kit.  If you tinker with your rifle, or have any other need to regularly check the power of your airgun, you should definitely take a look at this one in the list of chronographs for airguns.

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4. Caldwell 1006314-SSI Ballistic Precision Chronograph G2 – multi, N/A £360.99

chronographs for airguns

Best for accuracy

Spec:

  • Accuracy tolerance of 0.25%
  • 48MHz processor
  • Integrated lithium-ion battery

+ Comes with adjustable tripod
+ Lots of extra data to measure accuracy
+ Comes together quickly and easily
+ Also measures powder burners and bow users

The  Caldwell Chronograph G2 is also designed for powder burners and even bow users, capable of measuring projectiles up to 9,000 feet per second. Presented in a carry bag, the G2 comes with its own tripod, which can be adjusted between 80 and 170mm high.

There are a couple of plastic brackets that form a platform and contain integral LED lights, and some metal tubes which slot in at an angle to hold a unit that contains both the sensors and the other technical gubbins.

There’s an integrated lithium-ion battery which will give a run time of between two and 12 hours, depending on how much the lights are used.

The G2 provides a large area through which to shoot, which is handy as Caldwell recommends standing 10 to 15 feet away, though I’m sure you could get away with being much closer when using an air rifle.

The whole contraption snaps together quickly and easily, and the tripod provides a stable and versatile platform. A screen at the top of the chronograph provides a basic velocity readout. Three buttons switch the unit on and off, enabling you to select the units you want to measure in, as well as operate the lights.

Where the G2 really comes into its own is the fact that it can be paired to a smart device by downloading a free app to provide much more detail such as energy readings, average muzzle velocity, weather conditions and barometric conditions, all of which can be stored for later analysis.

Airgun Shooter Verdict: For the all-round shooter, the Caldwell Chronograph G2 is ideal. It’s well designed and made, and the Bluetooth connectivity feature not only makes it easy to use, but means you can log data on a wide range of different guns. Airgunners will need to be a little more precise, but there’s no doubt it will do the job.

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