Can I trust my Chrony?

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adamg

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I have a distrust of the numbers my Chrony tells me. It always shows me huge extreme spread numbers, like 80 on a 880fps pistol load or 150 on a 2600fps rifle load. Now maybe it is my reloads, which are loaded on a progressive. I do have a Chargemaster 1500 on order so I'll finally be able to build ammo that I know for sure has consistent powder charge.

How accurate are these chronographs we run? Can they really and repeatably measure a bullet to the 1 fps? Or is there always a degree of noise in their results?

I'm strongly considering borrowing a few chronos from buddies and stacking them inline to see how consistent they with others.

Are the optical-type $100 chronos hopeless, and a person needs a magnetospeed or radar?
 
Magneto speed works the best for me and regular chronographs work in good light and if the Chrono is far enough away from the muzzle. I found it helps to shoot lower through the uprights, just don't hit it.

I think a 5fps spread error more believable for a good 1.
 
The Chrony is very accurate. It has a high clock speed. I do not know if it sees 1 fps variations in a 2600 fps rifle load. But I can get single digit SD readings on 3000 fps loads.

The Chrony has to be used carefully to get good results. Shoot on an overcast day for best results. It will not give good readings against a blue sky. Use the skyscreens.

Bullets must be fired over the same path through the screens. Aim at something.

I find that backing up helps. I shoot at 20 feet.

I have seen 7 Chronys in line, with an Ohler in the middle. Results were excellent.

It will read a BB gun, an arrow, and a 22-250.

Poor neck tension or an inappropriate primer can give you a big ES.
 
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if you shoot at them too close you can get higher velocities when it reads the air going over the screen
I have found 12 feet min works ok
8 feet and you will get off readings ( unless its a pellet gun or a arrow)
 
Ganderite said:
The Chrony is very accurate. It has a high clock speed. I do not know if it see 1 fps variations in a 2600 fps rifle load.

The Chrony has to be used carefully to get good results. Shoot on an overcast day for best results. It will not give good readings against a blue sky. Use the skyscreens.

Bullets must be fired over the same path through the screens. Aim at something.

I find that backing up helps. I shoot at 20 feet.

I have seen 7 Chronys in line, with an Ohler in the middle. Results were excellent.

It will read a BB gun, an arrow, and a 22-250.

Poor neck tension or an inappropriate primer can give you a big ES.
Click to expand...

I find that, for rifle, 16 feet is all you need, and for pistol, 10 feet - this is the distance used in competition.
 
Good advice above. If in doubt, grab a box of good .22 ammo and see how that performs. I've found it to be pretty consistent.
 
Ganderite said:
The Chrony is very accurate. It has a high clock speed. I do not know if it see 1 fps variations in a 2600 fps rifle load.

The Chrony has to be used carefully to get good results. Shoot on an overcast day for best results. It will not give good readings against a blue sky. Use the skyscreens.

Bullets must be fired over the same path through the screens. Aim at something.

I find that backing up helps. I shoot at 20 feet.

I have seen 7 Chronys in line, with an Ohler in the middle. Results were excellent.

It will read a BB gun, an arrow, and a 22-250.

Poor neck tension or an inappropriate primer can give you a big ES.
Click to expand...

I also found that if the sun is low and hits the sensors it will give false readings,I sometimes tape a piece of cardboard onto the rods to keep the sun out,makes a big difference
 
I've obtained single digit spreads with my F1 and certain load combinations with both IMR/H4831 as well as Varget.
My biggest spreads are always ball powders, even though they meter great, they seem to have a strange burn characteristic I can't nail down or explain...tried different primers, different neck tension, same results. Can you still shoot 100m sub-moa groups with a 100fps spread? Absolutely, makes little difference at that distance.
I think they work fine.
 
adamg said:
I have a distrust of the numbers my Chrony tells me. It always shows me huge extreme spread numbers, like 80 on a 880fps pistol load or 150 on a 2600fps rifle load. Now maybe it is my reloads, which are loaded on a progressive. I do have a Chargemaster 1500 on order so I'll finally be able to build ammo that I know for sure has consistent powder charge.

How accurate are these chronographs we run? Can they really and repeatably measure a bullet to the 1 fps? Or is there always a degree of noise in their results?

I'm strongly considering borrowing a few chronos from buddies and stacking them inline to see how consistent they with others.

Are the optical-type $100 chronos hopeless, and a person needs a magnetospeed or radar?
Click to expand...

They are rated at 99.5 % accuracy; which on a 3000 fps load is already + or - 15 fps. That's when they work. We lined up 3 chronies and they were within 100 fps of each other most of the time. I consider a day a roaring success if one catches 4 out of 5 velocities, so if you don't even know if its going to work at all why should you believe the rest are right? From what I see, many users just ignore every velocity they don't like. Then there's the anomolies like a .300 Win with 180s that consistently clocked 3500 fps until it decided to start spitting out 3150s when the sun moved a bit.

I believe the targets and the long range drops and don't believe much else.
 
I've had a Chrony Beta I felt the same way you do about it, I was suspicious. Then I checked when I person I know showed up at the club with a Doppler. The Chrony was consistently between 100fps to 200fps slower that the Doppler.

I sent it for recalibration.
 
The chronys are good.

As ganderite said here are a few tips for the chrony

-Over cast days or have the chrony set up in a shaded area.
-Have the set up 3-5 yards away from the muzzle to minimize the muzzle blast having a effect.
-A leveled set up, I use a cheap camera tripod with a bubble level
-Aim for the brass bar joint area, you can't really shoot for groups and use the chorny at the same time imo.

Keep in mind the chrony is unreliable to find the absolute muzzle velocity there will be some deviation from set up to set up. But it is very good at finding the deviation between shots.

Its not a bad tool to use at the range when ever you are working up a load, its there to tell you if your loads are too hot and how your loads relate to the load data.

It tells the shooter the consistency of his loads so he is not chasing groups.
 
I thought mine was reading off......but then I compared it to a magnetospeed, and all the numbers matched up within a couple feet per second. *shrugs*
 
Yes, when in doubt, line up 2 Chrony's to check the consistency of close between the 2 of them.

Example might be:

Chrony #1 reads 3000,,,, Chrony #2 reads 2980... Spread of 20 ft-per second give or take.

After 3 or 4 shots the over all spread between #1 & #2 should show a pattern. At least we it does.

If they remain close to 5 to 20 ft-per seconds over all, then things are working out in that department.

If you know someone with a Mag pro, ask them to Mag pro & shoot threw your Chorny to give you the actual ft-per seconds.

Use this difference as the actual till you test it again next year.

Don
 
Chrony...they should be within 20-30 fps. Labradar is claimed to be 0.1% accuracy, so aprox 2-3 fps on most loads
 
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