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Combro CB-625 Chronograph Review
In
our December news pages, we commented on what we felt were a range of perfect
Christmas gifts that could be used by any Airsofter, regardless of the kit they
used. One of these items was a Chronograph, which for most Airsofters,
especially those that like to tinker with their guns, is an invaluable tool. If
you weren't lucky enough to receive one this year, and need to buy one
yourself... we look at one of the most affordable, and tiny Chronographs on the
market, the Combro CB-625 MK4.
The CB-625 is manufactured and
distributed in the UK by Combro, and is one of the cheapest Chronographs
available. Priced at only £39.95, available direct from the manufacturer, it is
packed with a host of features most Airsofters will find useful. Although it is
best marketed towards the airgun shooter, it is possible to use the CB-625 with
most AEG's, Bolt action and fixed barrel airsoft guns (excluding of course,
models like the TM shotgun range). It is very tricky to use with gas blowback
models, as the vibration and movement cause the barrel to become misaligned from
the sensors, resulting in a bad reading, or worse still damage to the unit
itself (believe me, I've done it!).
Out of the box, the MK4 is capable of providing information in both feet per
second + ft/lbs or metres per second + Joules. Airsofters are really only
interested in the feet per second read out, as most of us have to adhere to the
328fps rule with a 0.2g BB in the UK. The unit is also capable of providing you
with the highest fps recorded, lowest fps recorded and an average number, all
three of these readings are very useful, especially when calibrating an Airsoft
gun during an upgrade. It is quite tiny compared to the Chronographs a lot of us
are used to seeing at Skirmish sites, measuring only 150mm by 49mm and that
includes the barrel mount, and weighing only 55 grams. Combro claim it is over
99% accurate, and it is capable of measuring up to 2000+ fps, of course, that
would be one ridiculously powerful Airsoft gun!
This model is also capable of sending data to a PC via a serial interface, which
can be used to plot performance graphs, and an electronic layout diagram is
included in the instructions for the pin-layouts, or you can purchase an
interface lead from the Combro website.
The construction is of good quality, high impact black plastic, which also
includes a sliding 'V' shaped mount which assists in aligning the unit with the
end of the barrel. This works well with most guns that have a round flash-hider
on the end, and will accept sizes of 12mm to 32mm, by simply adjusting the
height of the 'V' mount. Care needs to be taken when operating the unit that the
alignment is precise to the centre of the barrel, or the BB (or airgun pellet)
may strike the plastic outer casing and damage it. I have been a victim of this,
which you can see in the photos, but luckily it did not affect the operation of
the unit. The instruction leaflet details spares that are available, including a
repair service should you be unlucky enough to damage it.
The LCD display shows a number of icons, which are clearly explained in the
instruction leaflet. The CB-625 is also capable of displaying a message stating
'FAC' whereby a gun has exceeded the pre-programmed power levels, or 'LEGAL' if
it's within the allowed range. These figures can be adjusted as mentioned
previously to read out ft/lbs or Joules. Within the UK the legal limit on Air
Rifles / Air Pistols is 12ft/lbs and 6ft/lbs respectively. Do not confuse these
figures with the limits on Airsoft weapons, as an Airsoft rifle shooting at
12ft/lbs, with a 0.2g BB would inflict SERIOUS injury (if it was even possible
to upgrade it to that level). Combro warn in their instruction leaflet that
excessive muzzle blast can damage the unit, therefore it is not advised to use
on rim-fire or centre-fire firearms.
In operation, it is very simple to use. Simply press the RST button to turn the
unit on, align it with the barrel and fire. The unit will display the velocity
in feet per second as the default measurement, but you can change this to metres
per second should you require. Pressing the PDS button after your shot will give
you a reading in ft/lbs, measuring the power of the shot, but in order for this
to be accurate you need to set the pellet weight. Again, this is also capable of
displaying this data in 'Joules', which is what most Airsofters refer to, 1 Joule
being 328fps with a 0.2g BB. Remember to press the FPS button again afterwards,
as the CB-625 remembers the last 'mode' you were in, and displays all subsequent
data in this format. You will need to press the RST button between each shot, to
clear the last read out.
Holding down the FPS button will first display the average over the number of
shots fired, followed by the lowest, and then highest numbers until the button
is depressed. To clear the CB-625's memory, just hold the FPS and PDS buttons
down together, until the display shows '000'.
Setting the pellet weight in order to measure power is a matter of holding down
the RST button, the unit will then show the 'test display screen' which will
then disappear, continue to hold the RST button down until it displays a number
with the wording 'GNS' underneath, this is the pellet weight in 'grains'. To set
the pellet weight for a standard 0.2g BB, you will need to enter 0.30 (0.30
grains = 0.20 grams), or you can set the unit into Metric mode, enter in 0.20
and then switch it back to Imperial.
Holding the RST button down beyond the pellet weight screen will take you, in
order, to the following screens:
GB - (Imperial = fps) or Eur (Metric = metres per second)
Power Screen - This is where you enter your limits to display 'LEGAL' or 'FAC'.
Calibration - This screen allows you to calibrate the unit, enter 0 for 1% fast,
199 for 1% slow or 100 for no correction.
SND - Serial Link test, in this mode pressing the FPS button will send a 280fps
shot, and the PDS a 810fps shot.
For more detailed instructions and further information on this unit, visit
http://www.chronoscopes.com/manual/index.html
where the instruction manual, and a
'virtual model' are available to play with.
Conclusion
The CB-625 offers a highly affordable and functional chronoscope that is very
useful for calibrating AEG and Bolt Action Weapons, and any non-blowback gas
pistols. It is however, extremely difficult and possibly damaging to try and
chrono a gas blowback pistol using this unit. For £39.95 I believe it to be very
good value for money, and would recommend it to anybody who does their own
repair or upgrade work, don't risk taking your gun to a skirmish site to find
out you're over the limit!
The CB-625 is available direct from Combro UK. Visit
http://www.chronoscopes.com/ or
Phone UK: 01323 899950 World: +44 1323 899950.
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