Q I’m new to shooting and keep reading about chronographs. Why are they so important? A
A CHRONO HAS been a vital tool in the airgunner’s kit bag for many years. The first reason a chrono is important is to keep your shooting within the law, and testing your air rifle or air pistol brings peace of mind. Testing also gains an insight into how any airgun is working, and a favourite airgun run over a chrono may yield surprising results.
What you thought was a hyperpowered supergun could be totally duff. And a well-loved 1970s BSA Buccaneer in .177 might crack like a rimfire every shot, but on testing could be found to be only doing 4.5 foot pounds. Many airguns still perform well on target when they are in fact leaking or hiding faults with ageing power plants. Servicing or a custom tune can benefit some airguns, but this won’t be evident until you use a chronograph.
Power isn’t everything, and in fact is far less important than many would have you believe. That’s why so many target air rifles only output six foot pounds as that is all that is needed to drill a neat hole in a paper target at 10m. For hunting, in the past terms like ‘high power’ and more worryingly ‘full power’ were used to describe performance. A chronograph helps bring clarity.
Relying on busy gunshops to chrono depends on how much you trust the experience of the staff and how busy they are, but for most of us it is the default place to bring a gun for testing. Recently a lot more chronographs have appeared, making it very affordable for near enough everyone, and certainly a club, to test their own kit.
Learning about any given chrono, however, is a must, with practice a necessity otherwise readings may be off. A test at a gun shop can still be used as a comparative reading against a test at home or over the club chrono at the range. Some chronos can be jacked to share readings into a computer or laptop, which is useful, especially if a record of any chrono session is wanted.
When using a chronograph, some accessories really help, such as weighing scales. These verify the pellet’s weight before this vital data is input to the chronograph. Errors in weight will mean errors in the recorded power and muzzle velocity of the airgun being tested, and that’s important when hand-picking pellets for shot-to-shot consistency. Temperature is relevant when testing CO2 airguns, and a thermometer is another very useful tool.
Self-testing has never been easier or more affordable. Barrel-mounted chronos such as the Combro have stood the test of time. A larger standalone mains-powered chronograph allows greater workflow if testing in greater detail, or when handling a number of guns over one session.
If the gun is legal and no faults are present, the other reason why a chrono is invaluable is as a tuning aid. The best pellet for any gun may not be the one with the highest power over the chrono, but testing a wide selection of pellets gives an indication of which pellets are leaving the barrel with little effort and giving good power.
From this reduced selection then, some accuracy testing is conducted downrange. The process may have started with eight or nine pellet types in different weights, but may be reduced to only one or two. The vital process of chronographing is actually good fun and not something to be treated as a chore.