How accurate is your chronograph?

[Airgun-Revisions]

don’t know but as long as it shows consistency and the pellet goes “whack” on a squirrels face it’s good enough. I have the fx

(full disclosure - i make chronographs)
My devices have (this week) got back from the Australian National Measurements Institute - so I have traceability on those "master" chronographs.
From those master Chronys I calibrate every chronograph I sell, so you know that the readings mine give are accurate, and can be traced to the standards.

So yes - there's mine, I believe SKAN also have one that is calibrated.
SKAN claim 99.6% accuracy, thats 4fps @ 1000
I've been able to get at least 99.9% accuracy, thats 1fps @ 1000 (actual results were around 0.3fps)
Prior to that - i had them back to back with the "most expensive radar" & over 20 shots @ 850fps, it was 1fps difference using the average.

I'll be doing a few "calibration" videos on my YT channel shortly - probably the biggest variable: EXACTLY how close are you to the muzzle?
I've been able to measure 3.5fps (from memory) decrease in speed 140mm from the muzzle!

I was chatting with a guy here that makes ballistic materials for police/armed forces, he has a $100k chronograph he gets tested every year. There's things that they dont even account for in their calibration, as its kind of impossible to incorporate.

This is exactly what people need to know and what I was getting at.

One more Question sir, how often should a store purchased chronograph typically be checked to determine it’s functioning as it should with a known Standard? Or do they not ever need to be checked?

 

[PasadenaMike]

We’re not sending astronauts into space we’re just checking the health of our gun and or just setting for optimal velocity. I take my chronograph out only when something feels off

 

[NateChrony]

We’re not sending astronauts into space we’re just checking the health of our gun and or just setting for optimal velocity. I take my chronograph out only when something feels off

True... but...
I know of more than a couple bench rest people that are expecting (assuming?) that if a Chronograph reads xxx fps, then its accurate to 1fps - which may *not* be the case.
If the Chronograph readings are jumping +- 2-3 fps, that's a spread of 5fps & something that a lot of people would work to remove. Not having a good known chronograph could be causing people to do unnecessary work.

Some chronographs also read to 1 decimal place, does that mean they're accurate to 1 decimal place?
I calibrate mine to 1/100th of a FPS @ 1,000fps, using an average of 10 shots. I wont put a decimal in my readouts as its basically marketing & just takes up screen space.
It really just does mis-lead consumers - but thats marketing

 

[PasadenaMike]

True... but...
I know of more than a couple bench rest people that are expecting (assuming?) that if a Chronograph reads xxx fps, then its accurate to 1fps - which may *not* be the case.
If the Chronograph readings are jumping +- 2-3 fps, that's a spread of 5fps & something that a lot of people would work to remove. Not having a good known chronograph could be causing people to do unnecessary work.

Some chronographs also read to 1 decimal place, does that mean they're accurate to 1 decimal place?
I calibrate mine to 1/100th of a FPS @ 1,000fps, using an average of 10 shots. I wont put a decimal in my readouts as its basically marketing & just takes up screen space.
It really just does mis-lead consumers - but thats marketing

Good point I guess it depends on what you’re doing

 

[NateChrony]

This is exactly what people need to know and what I was getting at.

One more Question sir, how often should a store purchased chronograph typically be checked to determine it’s functioning as it should with a known Standard? Or do they not ever need to be checked?

Not a bad question!
Ageing of the timing crystal occurs, however most ageing occurs in the first year & then logarithmically drops off.
You can also "pre-age" the crystals so this helps to reduce that factor. Does your device contain a 1year old or pre-aged crystal? (good luck finding that out)

If you're going to worry about that, you'd need to have it sent to a proper lab that has traceability back to international standards.
You're looking at around ~$1,000 (AUD) to have your device tested,

You could definitely get them checked, it *could* (not pre-aged etc) have reasonable impact on the performance, but knowing that is a very high cost.
IMO not worth the effort for the average user & finding a place that can do it, is a right PITA - a lot of places wont touch uncommon devices in my experience.
There's also errors due to temperature! every 10deg outside of 25dec could be up to 3-4fps @ 1,000fps of timing... so you're testing at 25deg right?

You could worry yourself silly - trust me on that one.
Get a device that a manufacturer has gotten independent testing on & you've done the most you can be reasonably expected to do.

 

[Treefrog]

This is exactly what people need to know and what I was getting at.

One more Question sir, how often should a store purchased chronograph typically be checked to determine it’s functioning as it should with a known Standard? Or do they not ever need to be checked?

Good questions.

I really have no idea. The assumption on my part is that it's consistent enough to suit my needs and will remain that way. I'm not aware of a readily available primary standard that it could be tested against. Although I have wondered about that...

An object of known weight and BC dropped from a pre-determined height should offer a very consistent result (given adjustment for variance in air pressure and humidity). Perhaps a one-ounce lead ball from a height of ten feet.

Cheers,

J~

 

[ThomasT]

A chronograph Is a device that measures speed. Most all measuring devices or tools can be checked or calibrated in some way by using what’s called a standard that’s traceable to NIST
(The National Institute of Standards and Technology)
My question is how do YOU know if your chronograph is actually functioning accurately? Do you even know if it’s accurate when it’s new? How do you check your chronograph to make sure it’s accurately reading true?

Hello @Airgun-Revisions

I am curious, how accurate do you expect a chronograph needs to be for the average air gun user?

ThomasT

 

[Wildcatter]

I have an old Gama Chrony, that is within 3 fps shooting a 3375 fps 6ppc, when compared to my gunsmiths 3 screen Ohler 33. One of the most proven Industry leading Chronographs ever made. His gets tested every 3 years. We also shot my crossbow thru both, 347 fps, same with both within a couple tenths of a fps.

I have checked it with a couple other buddies magneto-speed, and a pro Chrono, all within 5 fps of each other shooting 3200 to 3600 fps rifles.

The easiest way to get false readings is setting one up. Not shooting perfectly paralel across the sky screens, and on a two piece like the chrony not open properly. This changes the distance between the screens. The bullets path has to run parallel to the screens, so both have to be same exact line of sight to the target.

But for about 15 years the little chrony has always tested spot on. I think most all cronies are, when they are aligned properly to both the projectiles path, and the path square and parallel to the target.

For me, crossbow, airgun I expect spot on! But that is because I shoot centerfire Benchrest Rifles, both 100-300 yard short range, and 600 yard. My ammo has to be perfect, not just accurate, but single digit Extreme Spreads are mandatory when you need less than 1" 600 yard 5 shot groups to win.

 

[Wildcatter]

I'll add those tests are always run as 5 shot averages. Never one shot compared only, as most projectiles from the same gun with perfectly tuned ammo or guns can have spreads in the teens or more. 10 shot strings would be even more exact when testing against multiple chronographs.

But even tests against unconfirmed chronographs are pretty reliable when both read within single digits of each other.

 

[WNYBill]

I had a $100 Chony, with the PB 10 shots almost in the same hole and the chony was all over the place (+- 200 fps). 10 shots all over the target and the chony said +- 25 fps. My UN SCIENTIFIC findings, Chony didn't tell me anything about accuracy and I am back to measuring groups. Maybe a $1K chony would be more consistent.
I don't care how fast they are going, just want them all in the same hole.

 

[CharlieF]

Perfect is the enemy of good enough. My FX Pocket Chrony is good enough.

 

[Sawney Bean]

I had a $100 Chony, with the PB 10 shots almost in the same hole and the chony was all over the place (+- 200 fps). 10 shots all over the target and the chony said +- 25 fps. My UN SCIENTIFIC findings, Chony didn't tell me anything about accuracy and I am back to measuring groups. Maybe a $1K chony would be more consistent.
I don't care how fast they are going, just want them all in the same hole.

I've had 3 or 4 of those "shooting chrony's" over the years and I hate them. I got far more err1, err2 or err3's than I ever did usable readings and it didn't seem to matter how I arranged the shields or the lights. Sometimes you'd just set it up perfect with the sun at 38 degrees and Saturn in the third house and then you'd get a string of usable readings, but the next time you'd do the exact same thing and just get error after error after error.

I'm convinced that the primary reason so many of them got shot was due to people trying to shoot as close to the sensors as possible in hopes of getting an actual reading.

 

[Wildcatter]

I've had 3 or 4 of those "shooting chrony's" over the years and I hate them. I got far more err1, err2 or err3's than I ever did usable readings and it didn't seem to matter how I arranged the shields or the lights. Sometimes you'd just set it up perfect with the sun at 38 degrees and Saturn in the third house and then you'd get a string of usable readings, but the next time you'd do the exact same thing and just get error after error after error.

I'm convinced that the primary reason so many of them got shot was due to people trying to shoot as close to the sensors as possible in hopes of getting an actual reading.

Shooting to close to the screens is what makes them give more errors. I don't own the cheap red one, but the Gama chrony is as reliable as any I've used. You have to understand how to set them up, and keeping the bullets path to the target parallel to the screens is first priority.

Then understanding the closer to the screen the more exact your bullet has to travel to the center of them. I like to be 6" to 10" above the windows on the screens. Those screens are like a depth finder, the farther away the diameter they see grows, the light is constant.

Lastly, you have to use a cotton ball once in a while with canned compressed ait to dust the sensors, dust particles on the skyscreen is bad.

210 fps to 4200 fps my Chrony is spot on
But even the Ohler 33 can be bad on rare occasions.

 

[Wildcatter]

I had a $100 Chony, with the PB 10 shots almost in the same hole and the chony was all over the place (+- 200 fps). 10 shots all over the target and the chony said +- 25 fps. My UN SCIENTIFIC findings, Chony didn't tell me anything about accuracy and I am back to measuring groups. Maybe a $1K chony would be more consistent.
I don't care how fast they are going, just want them all in the same hole.

200 fps? That's either setup, or emiadiatly needed sent back! They all make a bad one now and then.

 

[357cal]

The ProChrono DLX, crafted by Competition Electronics, is a ballistic chronograph tailored for the precise measurement of projectile velocities. Key features include:

Enhanced Precision: The ProChrono DLX features an upgraded internal shot clock, which ensures improved accuracy to within +/- 0.5% or better.

Utility: A chronograph is instrumental in gauging the velocity of bullets, pellets, or other projectiles upon leaving the gun barrel. This velocity data is crucial for ballistic calculations, trajectory forecasting, and fine-tuning for accuracy. In hunting, it provides the essential information needed for an ethical kill. While no tool is flawless, the absence of a chronograph is unimaginable for me. (should be 10 feet to 3 meters away from your chrono)

 

[Airgun-Revisions]

Hello @Airgun-Revisions

I am curious, how accurate do you expect a chronograph needs to be for the average air gun user?

ThomasT

I don’t expect any crony to be the same or highly accurate and I kinda said what it needs in order to be that accurate. There was a multiple purpose to this thread. The first one was It never gets discussed and most of your newer shooters within the last couple years are truly under the wrong impression and that is their crony is always right.
What’s happening here is informational and needs to be read by others and have a true understanding about using crony’s.
Most all these comments are great and needs to be read.
I’m also standing up for Airgun business as well. You couldn’t imagine how often an Airgun dealer or builder hears from a customer that a gun isn’t shooting like it should when in fact it is. To many variables and crony’s not working as should be, or user error. Again not talking about the seasoned guys who knows better. They are actually commenting and teaching others within this thread now.
Personally just trying to stop the nonsense that some are holding chronographs to a higher standard no matter what. It’s impossible, especially when comparing two of them from different shooters and different locations on the map.

 

[Florida_Man]

I did a comparison since I have access to a labradar, currently I have the new one on order for work, and they are consistently accurate enough for my needs. I plan on updating that thread when the new labradar arrives.
I currently have 4 different chinese models to compare.

Like Jim, I use mine for tuning. The exact FPS is not important to me. I’m never looking for a specific number, just a sweet spot.

Chinese Chronograph vs Labradar

I bought a cheap one to adjust the hammer spring instead of setting up the labradar every time. And I can shoot into a box on my back porch. It's just more convenient to have something like the Chinese thing. I tested it against the Labradar to see if its worth the time. I think it does an...

www.airgunnation.com

This model is currently my favorite, although it is not the most durable feeling instrument.

 

[357cal]

I don’t expect any crony to be the same or highly accurate and I kinda said what it needs in order to be that accurate. There was a multiple purpose to this thread. The first one was It never gets discussed and most of your newer shooters within the last couple years are truly under the wrong impression and that is their crony is always right.
What’s happening here is informational and needs to be read by others and have a true understanding about using crony’s.
Most all these comments are great and needs to be read.
I’m also standing up for Airgun business as well. You couldn’t imagine how often an Airgun dealer or builder hears from a customer that a gun isn’t shooting like it should when in fact it is. To many variables and crony’s not working as should be, or user error. Again not talking about the seasoned guys who knows better. They are actually commenting and teaching others within this thread now.
Personally just trying to stop the nonsense that some are holding chronographs to a higher standard no matter what. It’s impossible, especially when comparing two of them from different shooters and different locations on the map.

What I often see is not so much the difference in the type or brand of chronograph, but rather incorrect setup. Have the muzzle 10ft or 3 meters away from the chronograph.

The margin of error for chronographs can vary based on several factors. Here are some practical tips to increase the accuracy and reliability of a chronograph:

Lighting Conditions: Ensure consistent lighting for accurate readings. Overcast skies are ideal, while direct sunlight should be avoided. If in shade, remove diffusers.

Chronograph Placement: On sunny days, place the chronograph in the shadow of a building or an opaque wall. Avoid the uneven, dappled sunlight from trees.

Clean Skyscreens: Dust accumulation can affect accuracy. Gently clean the sensors using a Q-tip or compressed air.

Level the Chronograph: The calculations assume a bullet path perpendicular to the sensors. If the bullet travels at an angle, adjust the velocity calculation accordingly. For muzzle velocity, add roughly 0.75 mph for every foot of distance from the muzzle.

 

[NateChrony]

I have an old Gama Chrony, that is within 3 fps shooting a 3375 fps 6ppc, when compared to my gunsmiths 3 screen Ohler 33. One of the most proven Industry leading Chronographs ever made.

The Oehler 33 has a 1 Mhz clock, with 3ft spacing 3000fps vs 3003fps is pretty much exactly 1Mhz!
1Mhz is pretty slow & limiting, however it overcomes that with very wide spacing between the sensors. If we're splitting hairs with diabolo pellets - could be a slight issue. Larger devices (can) make for better accuracy, but the tradeoff is setup & space.

 

[NateChrony]

The margin of error for chronographs can vary based on several factors. Here are some practical tips to increase the accuracy and reliability of a chronograph:

Lighting Conditions......Chronograph Placement......Clean Skyscreens.......Level the Chronograph......

If you use a muzzle mounted system - all of that is taken care of.

These days its probably worth noting about the "types" of chronographs available, and the drawbacks etc...
Depending on what you're doing - the type is probably going to be most important before a particular brand.

Muzzle mounted
+ most reliable shot detection
+ true muzzle velocity
+ not affected by environment (lighting etc)
+ can be used in the smallest spaces
+ cost
- only for air powered (non-powder)
- could require cleaning (stored poorly, smoky springer)
- (they're going to be smaller, so limited to "lower speeds" - but nothing air powered is going over 2,000fps)
Shoot Through
- harder setup: more space required, alignment is critical
- affected by environment: lighting, can lead to unreliable detection
- typically larger form factor
- medium space required for usage
- could require cleaning (stored poorly, used with powder, smoky springer)
+ could be more accurate given sensor spacing
+ can be used on powder as well as air
+ cost
Radar
- Can be affected by environment (radar reflections), possibly harder to setup (what space is available)
- cost
- large amounts of space required
+ can be used for powder
+ can give BC readings