Looks like a new Chrono is next...

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Looks like a new Chrono is next...

Post by Rod_outbak » 31 Dec 2018, 5:33 pm

I think my 'Shooting Chrony - Master' chronograph has gone squirrelly.
Made in the good old US of A, and the gent who designed that user interface needs to be tied to a bull-ants nest...

The last few chrono results from this unit have become erratic, and I had the chance to test it against a mates PACT chrono today.
We fired 5 rounds from each of the following:
Ruger Precision Rifle .223 - mates rifle firing Hornady factory TAP 75gn loads
CZ 455 .17HMR of mine, using CCI 17Gn V-Max pills
CZ 455 .17HMR of mine, using CCI 17Gn Speer TNT pills
Tikka T3 7mm-08 of mine, using 120Gn V-Max reloads of mine
Ruger Precision Rifle .308 of mine, using 125Gn SST reloads of mine
Tikka T3 of my mates in .260, using reloads of his in 95Gn V-max pills.

We set the 2 units up one after the other, so we shot through both, with mine being second in line.
The PACT was about 3.5 metres from the muzzle, with my 'Master' about a metre further, and we got 'clean' reads on all shots fired(no errors).


Most of the groups tested as being 50fps faster through my chrono, though not all of them.

Most of the groups had nearly double the spread on my chrono, than my mates PACT chrono.

And yet, a couple of the loads came in nigh identical with my mates PACT chrono.

I've been through the poxed manual for the damn thing, and there's no function to re-calibrate the unit.
Besides; how would you?
About the only option would be using something that has a definite, repeatable & known velocity around the 3000fps mark, and there arent a LOT of those in outback QLD!
OR...using ANOTHER chronograph to test THE OTHER TWO chronographs!
[This will start to get convoluted...sigh.]

My theory is that the dust out here knocks the optical sensors around over time, and screws them up. It certainly seems to do that for other optical equipment, so cant see why an optical chronograph wouldnt be the same.

So, NOW I have to do a bit of soul-searching, and decide whether I am happy to go with a MagnetoSpeed chrono, or bite the bullet and go LabRadar.
I can justify either, as long as it works.
Both look to do the job, but the LabRadar appeals for the simplicity of use, and the more extensive mapping of each bullet's flight. The heavy power usage doesnt worry me, and it's unlikely I'm going to clock anything about 4000fps in this lifetime, so it's limitations wouldnt worry me.
I do like the idea of simply plonking it down beside me, turning it on, and firing away. ...

Decisions, decisions....
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Re: Looks like a new Chrono is next...

Post by brett1868 » 31 Dec 2018, 5:45 pm

Lab Radar...every day of the week :)
How's my posting?
Complaints, Concerns - 13 11 14
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Re: Looks like a new Chrono is next...

Post by marksman » 31 Dec 2018, 6:10 pm

IMHO I dont have a clue :wtf: :lol: :lol: :lol:
but this may help :drinks:

www.youtube.com/watch?v=8SpjRnYncpo
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Re: Looks like a new Chrono is next...

Post by straightshooter » 01 Jan 2019, 7:21 am

With all chrongraphs everything depends on what actually triggers the start sensor and what triggers the stop sensor and whether that variation is significant in relation to the distance between the start and stop sensors and in comparison to the resolution of the internal timing clock in the unit.
Virtually no consumer level chronograph can be used to obtain an absolutely reliable measure of velocity. What the manufacturers don't ever reveal is the true and reliable tolerance level on readings that may be obtained. At best it will be an approximation and will be most useful for comparison of similarly assembled ammunition.
All types ie; shadow triggered chronographs, magnetospeed and labradar have both strengths and weaknesses.
Some examples of what will be a source of error for a shadow triggered chronograph are:
Short distance between start and stop sensors.
Uncertainty as to which part of the projectile (ie: tip, ogive or body) generates the shadow triggering event in each of the start and stop sensors.
In a magnetospeed the relatively short distance available for detection must potentially impair absolute accuracy although repeatability may be OK.
I have no idea of the triggering mechanism within a labradar so I can't comment.
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Re: Looks like a new Chrono is next...

Post by Rod_outbak » 01 Jan 2019, 9:30 am

On my old CED Millennium chrono, there was an option to set the distance between the two optical sensors.
As the Shooting Chrony units use a set distance (Sky-screen mounts are integrated into the fold-open mount/box), there doesnt seem to be any option to adjust or re-calibrate the chrono. Certainly nothing in that POXED POXED POXED menu that suggests it can be edited.

But even more of concern, was the fact that my chrono seemed to vary it's results more than the PACT chrono we were comparing against.
For some groups, my chrono had a spread of double that of the PACT for the same shots, in some groups, my spread was nigh identical, and in some groups, the spread was over 3 times as high.
So, aside from trying one last thing to see if I can get a bit more reliability, I think the Shooting Chrony Master is to be retired.
When I compare yesterdays results against the results I took last week with 3 of the same rifles, my chrono seems to have them with notably higher velocities for the very same ammo as tested last time. Same time of day, exact same ammo (even same batch), and same temps/sunlight/etc etc.
Inconsistent.

From what I have read about the LabRadar units, they have an audio trigger (built-in microphones), can have external trigger devices connected, or using the doppler radar itself(depends on the type of projectiles, but the internal microphones recommended for firearms).

I'm leaning towards the Labradar for ease of setup & use, which equates to me testing loads more regularly.
However, I shall ponder it some more, before taking the plunge.
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Re: Looks like a new Chrono is next...

Post by Ziad » 01 Jan 2019, 11:27 am

I think i have said it superhersomewhere else. I got my nagnetospeed sporter for 250 from a shop...that's now closed. At that price it was a no brainer.

It does effect poi (and possibly groups, need to do more testing) but its very simple to install very small and works for me. If money was no object and the best was required then possibly the reputation of lab radar wawould male it the winner.

But got a shooting mate, hes got an optical one. ..not that he uses it a lot but his ammo is just superb. Even i can get some very accurate groping on my worst day.
Blame it on the phone auto correct
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Re: Looks like a new Chrono is next...

Post by Sako308 » 01 Jan 2019, 11:42 am

If you want an accurate velocity detection everytime with those calibers, then MagnetoSpeed is the go. Ive found with the MS that once you've setup the bayonet for height the first time, then you rarely have to mess with again, unless you're going from a heavy barrelled .22cal to a sporter barrelled big cal. but then its a simple matter of adding or removing a spacer and confirming bore clearance with the rod.

From what Ive read on the inter-webs the Labradar struggles with detecting small cal's, but I haven't had the opportunity to test it myself.
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