chrony reliability

[414gates]

I've got an F1 shooting chrony. The entry level model.

I loaded a batch of 44 special with 6.3 gr MP200 , 245 CMJ and I get an average of 600fps. This is of five 3 shot strings.

But, the consistency of the velocity reading depends on how close to the diffuser the bullet passes. If it's low over the sensor I get 40fps over or under 600. If it's higher up below the diffuser, the readings are more similar, with less than 10 over or under 600. These variations are not due to variation in the reloading process. I tested a batch of 60 rounds over the chrony, and every 10th charge was weighed, with no variation in mass using an RCBS electronic scale. Crimp and bullet length are firmly set and do not change.

I can't explain a 100fps variation in readings around 600fps from the same batch on the same day other than the unit is a dud.

On a completely overcast day, removing the diffuser completely works , as per the instruction manual of the unit, but the reading variation remains.

I've had it for a couple of years now, and I put a fresh battery in for the last test run. At one shoot, an identical F1 chrony was set up next to mine, and the readings were very consistent but higher than what showed on mine.

This is my first chrony, I've got nothing to compare it to.

Any thoughts from Shooting Chrony owners ?

[414gates]

I can possibly attribute the velocity variation to a weight variation in the bullets. There is a few grains variation in the weight, because these are plated cast, not plated swaged.

But deferring to almighty Google, and reading up on the different makes and models, it seems that the F1 Chrony is not the most sensible choice. Given how chronies work , the CED M2 has a more sensible positioning of sensors and the sensor distance is not just 12". There's also the infra-red option that I like, so it's light agnostic.

I'm most likely going to pack it up and send it back the factory it came from. They can frame it as an example of what kak not to sell.

[414gates]

The packing is done. It's going back to Canada with a note.

There's no sense in struggling with erratic equipment.

I'm getting a CED M2.

[THOMAST]

414gates
I had similar problems with the 2 Chronys' that I had.
I read a very interesting report over on a US shooting forum where a user with a mathematic &scientific background evaluated and tested several Chronys'. Reading through all the gobbledygook it was clear that he was stating that the electronic circuitry was part of the reason why you had so many inconsistencies in the readings, which most shooters would attribute to their reloading .(He was using a batch of .22 ammo which had been tested and found to give consistent velocities for his evaluation/experiment) The only pluspoint was that it was quick & easy to set up.
You wont be sorry with your CED.