Is my (new) chrony wrong?

[easyrider604]

When I shot IPSC, my Chrony was used to develop 45 acp loads for matches, loaded to 176-177 power factor. Before any stage, range officers would randomly select 3 cartridges from my mags, or even from the pistol I was going to shoot shortly.

I was never disqualified for using underpowered ammo.

So I would say that Chrony makes a reasonably accurate chrono, and given the data you shared, you have a good one, and there is no reason to believe otherwise.

 

[longleader]

It would be nice to have a really good top of the line chronograph. But they are pricey. Maybe one day……..

But I think there is still value in our Chronys, especially if we use them a lot, and in conjunction with reliable reloading manuals. Even if they may be a bit “fast” or a bit “slow” one can get a pretty good idea what they’re doing after a while, and hopefully can interpret the results and sort through the chaff.

Maybe 2649 fps isn’t entirely unreasonable with 52.3 gr. considering the variations in individual firearms, other reloading components, etc.

7th. Edition Hornady Handbook shows (with 23 ¾”bbl.) 2600 with 53.0 gr. and 2700 with 55.3 gr., which is in the ball park of what my Chrony tells me. My M700 CDL with 24” barrel clocks (with my Chrony) around 2750 with 56.0 gr., that’s with Hornady’s #3070 SP. Using the same lot # of powder, 53.0 gr. gave me a 5 shot average of 2614 fps.

As mentioned, you have to really careful when screwing the tripod attachment on, making sure that the Chrony remains fully extended. A very small difference there could possibly result in big differences and inconsistencies in your readings.

Light could also be an issue, I like bright overcast type days which provide lots of diffused light. If there are no clouds then the diffusers seem to help, providing the sunlight is strong enough.

 

[762shooter]

Pretty lucky to get that close, because the chronographs I see advertise as being accurate to 1%. That's 26 to 30 or so fps variance to be the built in tolerance.

I think that is a worst case scenario.

 

[Whelen B]

A buddy and I didn't actually doubt our chronys but for fun we set up our chronys side by side and fired three shots over each. The comparison proved they were both functioning well. The difference was in the 10fps range between units which one would expect using 250s at about 2500fps from our 35Whelens if memory serves. I bought mine about twenty years ago and it has yet to give any trouble - very dependable.

 

[snoopycda]

side by side would not be a very good test. end to end would be mor informative.

 

[legi0n]

I took a good look at the chrony. It's not a very precise assembly. I think they're calibrated at the factory with a known speed test. This would be way cheaper than machining extremely precise parts.
Thus I ditched the idea of putting up a 2 light system with a precisely delayed blinking since I don't know the distance between the sensors.

 

[downwindtracker2]

BCs vary with velocity,not that the stated BCs are all that firm anyway.Bullet companies don't fudge,but they do guess,err, computer calculate the BC.

 

[308BAR]

How far or close do you have it set up to the bench? Sometimes I notice the muzzle blast could throw the chrony off from properly reading a load. Sometimes a muzzle blast from the stall next to you could do the same thing.

 

[legi0n]

How far or close do you have it set up to the bench? Sometimes I notice the muzzle blast could throw the chrony off from properly reading a load. Sometimes a muzzle blast from the stall next to you could do the same thing.

the instructions say 5m for a high powered rifle
1.5m for shotguns

 

[rem338win]

Is this the same Chrony that told you that the 180gr bullets where flying out of that 30-06 at 3200fps? If it is, then it is definitely broken.

 

[John Y Cannuck]

My experience with Chrony's has been good, my experience with tables, is another matter. Read the fine print. Some of those tables are 'expected trajectory' and those that are actually shot, are fired under ideal conditions. Don't expect to duplicate them.
There are of course the other factors, their use of universal receiver barrels etc.

 

[22to45]

I have put two chronys one behind the other and fired three shots, all the readings were within 5 fps...
That convinced me. Most people I have seen who were dissappointed in chronys were sure they read slow... Like the guy at the range in Calgary, who fired his new 7mm STW over my chrony, and the 175 gr bullet went 2900 fps.. or my the guy with the 308 norma mag who was shooting 200 gr bullets at 2400 fps according to my chrony. I have got some wild readings in the sun.. but I find that if I set it up well shaded, and with good clear exposure to the sky, especially a cloudy sky, I get reliable readings. Like every other instrument, it needs the right conditions to work. I have fired factory loads, and got a velocity spread of 150 fps, and then right after that fired moly coated handloads in a moly coated diamond lapped barrel, and got a velocity spread of 7 fps. Just as you would expect. I trust mine...