Why aren't chronos consistent?

[SinisterWeasel]

Inconsistent chronos are really starting to annoy me and I can't understand how something so simple can so drastically different site to site. My own gun has been chronoed at 20fps different between one site and the next although fortunately always below 350, which is worrying as I intended to increase the fps. Once it was over but they changed the battery in the chrono and it was fine again.

My brother travelled for six hours to see me this weekend, mostly to play airsoft but he couldn't use his own gun as it chronoed at 355-360 but he was able to play a game last week with no problems.

Just a bit of a rant as this doesn't need to be a problem...

 

[Sitting Duck]

it is the site's chrono and more so the make....

My xcortech 3200 does "seem" to match my own sites chrono

They have had a few over time but think they gone back to xcortech 3200

they lost the funnel so had trouble chronoing some chubby suppressor guns

so they tried some others like the madbull type with readings on the side

But either they were $hite or busted too soon or they managed to get a funnel from somewhere

love my 3200 - can be picky sometimes numerous TOUT but daylight and hold gun as straight as possible

As for changing battery in chrono - think that answers the question

3200 just shuts down flashing low battery

most popular is xcortech - must be for a reason

often madbull can be 5% out I'm lead to think - that is a lot if ya close to site limit as you have found out

 

[Sacarathe]

Are you frustrated about inconsistency across the same unit at the difference times, across the same model but at different venues, across the same brand, across different brands, at testing with AEG/GAS/HPA?

I've been the same boat as you! I highly doubt I'll buy a non quick change spring weapon again, especially since I just bought a bunch of springs.

Again this is probably a lack of an industry wide body; If for example, the govt may be putting through legislation about the power (joules) of airsoft guns in the near future, but its rather pointless if they don't legislate on the reliability of the measuring tool. I'm sure they have a list of approved 'tools' but that does not mean they will mandate it.

I suspect that one of the reasons, in that legilsation, that the joule limit they specific results in around 20fps more than 350 fps with 0.2g is exactly to cope with inconsistency at the chronographs, the same with their upper limit for single shot, falls above 500 fps with 0.2g.

I get the impression that chronographs, for airsoft purposes, are not made to the same tolerances as those which measure much higher velocities.

As there is no governing body, there wont be a "measurement must be with this tool" - and thats good tbh, gives each brand and equal chance and makes them affordable for individuals.

 

[Lozart]

something so simple

Do you know how a chronograph works?

It measures the time taken for a projectile to pass through two separated beams of light. Now, in general terms any measurement of velocity calculated from travel time will be more accurate if it's measured over the greatest distance possible. "Proper" shooting chronos are relatively large for this exact reason. The smaller the unit is the better the quality of electronics needs to be to provide sufficient resolution to provide an accurate result. The higher the quality of electronics used the higher the price point tends to be so take for example the average Xcortech chrono. It's sub £100 and it's quite small so firstly you need to take into account that the measurement distance is quite short and that even taking into account the mass buying power and relatively low cost of electronics, the guts are not going to be precision instruments. Add to this the effects that ambient lighting can have on the sensors and you are piling inaccuracy on inaccuracy. On top of all that most places don't know how to spell calibration let alone actually have it carried out on a regular basis.

Now, in your example it's perfectly possible that the chrono your brother normally uses at his regular site reads low and that the sites chrono at your regular site reads high, all within a sensible tolerance on their own, but when you combine the tolerances they result in your brothers "perfectly fine normally" gun being over the site limit. That's the main reason I never try and get my guns right up to the limit allowable on site, I like to know I've got a bit of leeway.

Of course if you ever find yourself at the Malls with their regularly calibrated Skan chrono, if they say your gun is over, then it's over.

 

[GiantKiwi]

Of course if you ever find yourself at the Malls with their regularly calibrated Skan chrono, if they say your gun is over, then it's over.

Except when 2 other skan chrono's professionally calibrated 2 days before going to one of their events disagreed with their's, as I had once. Even had them, and their calibration certificates with me and they still reckon my 2 were wrong with readings of sub 1J and theirs claiming 4 guns were 1.4J..

 

[skarra333]

Indeed. The training at sites on how to calibrate and properly operate a chrono can as variable as the devices themselves, so we're left with - at best - computer says no sometimes.

 

[SinisterWeasel]

Do you know how a chronograph works?

It measures the time taken for a projectile to pass through two separated beams of light. Now, in general terms any measurement of velocity calculated from travel time will be more accurate if it's measured over the greatest distance possible. "Proper" shooting chronos are relatively large for this exact reason. The smaller the unit is the better the quality of electronics needs to be to provide sufficient resolution to provide an accurate result. The higher the quality of electronics used the higher the price point tends to be so take for example the average Xcortech chrono. It's sub £100 and it's quite small so firstly you need to take into account that the measurement distance is quite short and that even taking into account the mass buying power and relatively low cost of electronics, the guts are not going to be precision instruments. Add to this the effects that ambient lighting can have on the sensors and you are piling inaccuracy on inaccuracy. On top of all that most places don't know how to spell calibration let alone actually have it carried out on a regular basis.

Now, in your example it's perfectly possible that the chrono your brother normally uses at his regular site reads low and that the sites chrono at your regular site reads high, all within a sensible tolerance on their own, but when you combine the tolerances they result in your brothers "perfectly fine normally" gun being over the site limit. That's the main reason I never try and get my guns right up to the limit allowable on site, I like to know I've got a bit of leeway.

Of course if you ever find yourself at the Malls with their regularly calibrated Skan chrono, if they say your gun is over, then it's over.

I do understand how they work but my frustration is that a chronograph that is mathematically wrong doesn't actually work and if they are assumed to be X% wrong then you should be allowed the same percentage over the given limit. They are performing a simple mathematical calculation and shot-to-shot are consistent, it's just the inconsistency between manufacturers that is the issue. If it wasn't precise due to the reasons you give then surely you would expect the same gun to be giving highly varied results on the same chrono in different conditions? I haven't experienced this but maybe others have?

As I said I am just ranting , partly because he couldn't use the £70 scope he was eager to test for the first time (which I paid half for). Simple solution is just keep your gun around 330-340 like mine already is but he didn't want to swap the spring out for the third time when he had already been given the green light.

Sort it out world, you sod.

 

[K@rl]

Some sites are a little bit more relaxed. Especially if you are a regular. My g&g m4 is always 315-322. Don't know why it changes and because it's never more than 322 I have never really thought about it.

Now what I am about to say may be controversial but hay ho, if you are shooting 355 fps try increasing you hop to its max. I know it will mean endlessly fiddling with it to get it right again and I know it's a bit of a cheat. But under 350 is under.

 

[n1ckh]

I have found in all the sites I've been to (6 sites so far) 4 have used the same chrono device (don't know the name but its the big yellow box chrono's) & my rifles have all been under the limit & the other 2 are primarily paintball sites so they use a paintball chrono & this throws your fps reading right out.

My brother is an airsoft retailer & has told me that white BB's or direct sunlight can affect the reading of your bb. If a site is non-bio then I don't use white bb's for those reasons (also makes them difficult to see when taking incoming fire) & bio bb's are not white from the ones I use

 

[BrightCandle]

My own Chronograph has recently been about 10% low for some unknown reason. It used to be agreeing with the sites but now its just decided to be quite a bit wrong, new batteries did not fix it. I don't know why they go like this but its not even as if one particular model with clean batteries always works consistently.

 

[jcheeseright]

The reason one airsoft chrono may disagree with another is because they're mass produced in chinese factories and have no calibration at all. If the assembly person solders the second sensor 1mm further away on one then that chrono will read lower, likewise if the light 'gate' on another chrono is offset by a couple of mm in the other direction it'll read higher. That's just ONE factor which could affect the readings from a chrono, different batches of processors in different batches of chronos may perform differently.

One that always gets me is sites that chrono outdoors in direct sunlight... at black ops cribbs my 100% stock TM gun chrono'd 380fps five shots in a row on their chrono, obviously I called bullshit and realised that the sun was shining right down the tube, I asked to turn the chrono 90 degrees and try again because of the sun and surprise surprise 280fps.

Airsoft chronographs are not precision equipment and the people that operate them often don't understand entirely how they work. Unfortunately it's often a case of 'our house, our chrono, our rules', which I can fully understand. You get someone turn up to your site for the first time and their gun comes in hot on your chrono... do you A: take them at their word that it's fine, or B: trust your chrono?

 

[skarra333]

Airsoft chronographs are not precision equipment and the people that operate them often don't understand entirely how they work. Unfortunately it's often a case of 'our house, our chrono, our rules', which I can fully understand. You get someone turn up to your site for the first time and their gun comes in hot on your chrono... do you A: take them at their word that it's fine, or B: trust your chrono?

C. See what a 2nd / the backup Chrono says.

 

[jcheeseright]

not that many sites have a backup chrono, and even if they do you'd hope that they'd been compared and produced similar results. If a site has 2 chronos and they read 30fps different one of them is wrong so why would they use it?

 

[BrightCandle]

Quite a few sites don't even both to chrono at all presumably due to the issues it causes. Trusting everyone is a great idea except for the fact that every I have been too that doesn't chronograph has resulted in a severe injury from a BB, so its not exactly a solution! Sites need to generally do a lot better about understanding how to use chronos and measure gun power in general.

 

[jcheeseright]

'severe injury'?

people losing limbs and suffering major internal bleeding?

 

[ImTriggerHappy]

How do you get a severe injury from a bb?

 

[cyrexx]

By getting shot in the tip...........

 

[ImTriggerHappy]

By getting shot in the tip...........

Thats not a severe injury thats just an owie.

 

[K@rl]

No it's happened to me and its severe enough to make me sit out for 10 mins. I would mind but it was tucked in my sock.

 

[SinisterWeasel]

Some sites are a little bit more relaxed. Especially if you are a regular. My g&g m4 is always 315-322. Don't know why it changes and because it's never more than 322 I have never really thought about it.

Now what I am about to say may be controversial but hay ho, if you are shooting 355 fps try increasing you hop to its max. I know it will mean endlessly fiddling with it to get it right again and I know it's a bit of a cheat. But under 350 is under.

Funnily enough I had accidentally left my hop up on maximum as I had previously been checking it was lined up Ok and it only chronoed at 160fps with 0.25's. I can't remember the exact number but there was a 100fps difference between max and the bbs were flying level, which does mock the process somewhat.

Maybe someone could bring out a chronograph calibrator of some kind. Like a bolt gun they use to snuff out cattle and consistent to 1fps. Or perhaps a more intelligent and thought out idea.