HW/Weihrauch Chronograph Uses

A chrono is a useful diagnostic tool in assessing several aspects of any gun's performance, and in identifying suitable ammo, even for the mild-mannered old springers that I collect.

I do 15-shot strings. These include the 6.9 gr RWS Hobby and/or 7.3 gr JSB Exact (or the very similar JSB-made 7.3 Air Arms Falcon), as a "reasonable max speed" baseline (i.e., best velocity with a quality pellet). Then I shoot other ammo for comparison.

Most chronos will record the velocity variance over the string, and more importantly calculate the standard deviation, which I also note as a percentage of the average velocity. SD is a good indicator of how well the ammo suits the gun - an SD of 2% is fine for general use; 1% is likely ready for the target range; and the percentage is useful for comparing guns of different power levels.

Here's one of my typical data sheets - which I use for jotting down other relevant information as you can see. Running new strings occasionally is a useful "check up" on component wear, new batches of pellets, etc. I've kept these sheets for many years and frequently refer to them. This particular Diana 34 llikes the JSB 7.9 Exact best.

My chronograph is a cheap one, therefore i don't expect accuracy. Sole use is to compare
different pellets as well as different guns.

bob3006 said:

I recently purchased a .177 HW97k. All my shooting will be target only at 25 yards or less. On this forum I see members talking about using chronographs. What is gained, if any, from an accuracy standpoint using them. It appears to me that a velocity change would relate to a weak or broken spring problem, which the chronograph would identify. Am I missing something?

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Mapping trajectories for projectiles you plan on using in the field, getting a precise tune on your pcp. If you do not know velocity you cannot know your drop thus making it a crapshoot to hunt at anything other than PB range.

For springers knowing the velocity and spreads of different projectiles. Coupled with scope height above bore, velocity and weight + BC you too can know your exact hold at distances.... From 5-25 has a LOT more variation in trajectory more rapidly than most from 25-100.
Sometimes a pellet will just mate better with your barrel and produce more consistent speeds and accuracy than any other by a wide margin. Knowing your muzzle velocity is very important.. crucial.

For example. I know that at 899fps with a 25y zero on my gun with a height over bore of 65mm 25-50 will have only a 1.25moa slope, at 100 hold over 13.5 minutes. If I didn't know speed id have to shoot at every single 5 yard increment to get my turrets taped and sync'd

bob3006 said:

I recently purchased a .177 HW97k. All my shooting will be target only at 25 yards or less. On this forum I see members talking about using chronographs. What is gained, if any, from an accuracy standpoint using them. It appears to me that a velocity change would relate to a weak or broken spring problem, which the chronograph would identify. Am I missing something?

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I am in your boat as along time crony owner I am a seldom user. I did use my Garmin last month to confirm I did not all of a sudden forget how to shoot but had a spring issue. Other that that in my mind shooters win while technicians admire their testing. I know guys who are great practicing, run numbers, lube, weigh, measure, but can't do well in a match to save their life. Some things are hard to explain. So do you need a crony or a big dollar scale to be an excellent shooter, absolutely not. I admire the guys that do tons of work to makes things as perfect as possible, thats not me. But I will out practice most, pay a good mechanic to service my gun , ad then go do my best at a match which means I usually shoot better at a match then at practice.

bob3006 said:

I recently purchased a .177 HW97k. All my shooting will be target only at 25 yards or less. On this forum I see members talking about using chronographs. What is gained, if any, from an accuracy standpoint using them. It appears to me that a velocity change would relate to a weak or broken spring problem, which the chronograph would identify. Am I missing something?

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Your not missing a thing.

You bought a great rifle. They are excellent shooters. Very accurate.

Different pellets will give different velocities. So use the same pellet for a baseline. Springers will shoot a little faster or slower at different temperatures and altitudes. The brightness of the sky may influence the speed your instrument reads. Different chronos will yield a little different numbers. So take it all with a grain of salt.

Definitive drops in velocity indicate a problem with the powerplant. Spring, seal or breech seal. My HW97k has gone through a couple springs and it shoots as well with a broken spring as it does with a new one. Just slower and lower at range. It's a .22 so it will shoot slower than yours, but when mine goes below 600 fps. I'm thinking about a spring kit to rebuild it or send it back for warranty service.

It's a handy diagnostic tool. I use mine every month or so. It's not something you can't live without but sooner or later you will want one.

I use my chronograph (I've had 3 with the Garmin Zero being the best by far) for air rifles, crossbows, and vertical bows. With archery one of the things I've done is test the impact of different string silencing strategies as just one example.

I very rarely used the chronograph with my springers though. I would do an initial look see to determine if FPS/FPE was enough for squirrel hunting and to compare rifles.

I'd skip the chronograph if your only airgun is a springer. Zero it at 25 and figure out your holdovers to 50. If at any point it's acting odd, measure the 50 holdover again (with the same pellet of course and similar weather) and if the 50 holdover moves you probably have sufficent change in velocity to investigate further.

Chronographs are most important for competitors who are verifying their velocity for the rules compliance and for PCP shooters who are adjusting their tune. Its possible to tune a springer but it's not something most shooters do. I send mine to John Thomas 'John in PA'.

A speed check can alert you that something is wrong.
For tuners a chronograph helps them achieve what they intend.
If you shoot FT there are speed restrictions you must (SIC) comply with and you should know your power before entering the match as sometimes the MD will (SIC) check them.

A chrono is invaluable for anyone that reloads for their powder burners. Valuable for airgunners too, for things like calculating actual ballistic coefficients and checking the truthfullness of the advertisers.

Cheers,

J~

i have had the best , sold them , this is what i use now . oyu can find the same thing much less than this price .

beerthief said:

i have had the best , sold them , this is what i use now . oyu can find the same thing much less than this price .

Amazon.com

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I like that design!

My old crony and my Caldwell both have issues with the sky. The brightness and position of the sun really affect the numbers and cause lots of errors. I lay a piece of white bedsheet over the screens and let it drape down over the sides and it works better. If the sun hits one or both of the eyes it blinds them. I have to remember to take the cloth and a couple clothespins or I'm messing with it to get it to work.

It looks like that one faces down against that plate. Does it give comparable readings in different light?

A chronograph is some simple tech. They aren't worth much but you can pay a pile for some of them. A simple one like that is about all a fellow needs.

I have a very old chrony master beta (yeah, what a name) as well as a pro chrono, an incredibly cheap Chinese thing with built in led as well as a lab radar. They are all within a few feet per second of each other. Less than 10fps difference and this is across 15/20yrs of tech.

I would not care to be without a chrono. I would not bust the bank on buying one. My experience is that there is more error in readings from not aligning the sensors to the actual path of the pellet than in individual machines.

Star7 said:

I have a very old chrony master beta (yeah, what a name) as well as a pro chrono, an incredibly cheap Chinese thing with built in led as well as a lab radar. They are all within a few feet per second of each other. Less than 10fps difference and this is across 15/20yrs of tech.

I would not care to be without a chrono. I would not bust the bank on buying one. My experience is that there is more error in readings from not aligning the sensors to the actual path of the pellet than in individual machines.

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Nailed it. Angling in any way will give you wild readings... 860 862 861.2 861.5 1024.9 861...

Happens all the time and I've tested a cheap airsoft chrono against a prochrony, Garmin, and fx. The difference in readings were negligible. Obviously lab radars and the Doppler chronographs offer software which interface beautifully with other devices and give readings at several ranges. Which is nice. But as far as getting a muzzle velocity. Most will suffice to get you where you want.

Bedrock Bob said:

I like that design!

My old crony and my Caldwell both have issues with the sky. The brightness and position of the sun really affect the numbers and cause lots of errors. I lay a piece of white bedsheet over the screens and let it drape down over the sides and it works better. If the sun hits one or both of the eyes it blinds them. I have to remember to take the cloth and a couple clothespins or I'm messing with it to get it to work.

It looks like that one faces down against that plate. Does it give comparable readings in different light?

A chronograph is some simple tech. They aren't worth much but you can pay a pile for some of them. A simple one like that is about all a fellow needs.

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their are led lights shining up from the flat bottom sheet , the box and readout is on top .

The chronograph is a good tool for detecting problems with your airgun, letting you know the
airgun is shooting at, or close to spec, and experimenting which pellets to get the best efficiency
out of your power plant.

beerthief said:

their are led lights shining up from the flat bottom sheet , the box and readout is on top .

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That seems like a much more logical way to do it than having the little photo panels facing toward the sky.

That complete unit is less expensive than the LED skyscrèens for the Caldwell. They help a lot but the sun is still a problem at certain angles.

One like that might be a much better design.

Bedrock Bob said:

That seems like a much more logical way to do it than having the little photo panels facing toward the sky.

That complete unit is less expensive than the LED skyscrèens for the Caldwell. They help a lot but the sun is still a problem at certain angles.

One like that might be a much better design.

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I put the one i bought ($13) from china on the end of the barrel and then shot through my Caldwell . 10 shots later they basically matched ,1 or 2 FPS on one or two pellets . close enough for me .

I wouldn't even think about doing airguns without a chronograph. They are indispensable to knowing what you have and how it's keeping up.

There's no telling what even a brand new German springer shoots without a chrono. They commonly have (mostly fixable) issues straight off the factory. Any used gun, or a gun that has been worked on in any way, and it's a complete guessing game without a chrono. And contrary to one opinion upthread, many, many guys work on their own springers. To me, personally, that's easily one half of the game / enjoyment.

Springers are hard enough to shoot accurately that you'll be deep in a bog of uncertainty if are unable to isolate variables. Your shooting may not be accurate / consistent because of you, or because of the gun. The chrono tells you when it's the gun. There are dozens of potential reasons why a gun doesn't shoot up / down to spec, or not consistently enough. Just a piston seal that's a little too tight can slice 100 fps off the MV, or a gun that is dieseling a little too much can spread velocities by 30 fps, but you can't tell (easily), without a chrono.

With fixed distances, you could do with low velocities and still be highly accurate, but you couldn't do with inconsistent velocities.