A Tale Of Three Chrony's

A

alinwa

oft dis'd member
Another Alinwa anecdotal account....





I've always wondered;

How accurate are chrony's?

Are they "relatively accurate" in that they may not exactly tell you velocity but they'll show shot-to-shot variance OK?

Are they repeatable?

So today we finally got the perfect PNW testing day, uniform overcast but not raining. So I set up chrony's and shot over three in a row alla'sametime.

Chrony #1 is open to the sky
Chrony#2 has skyscreens on
Chrony #3 is artificially lighted

This is raw data from the last few hours. (I just got hungry...)

I'm skipping a lot, listing no loads but I've included representative strings from several tested powders. I'm running up to max loads using 112gr bullets in a 300WSM, testing powders from 'fast' to 'slow'.....

1st column is 1st chrony at about 10ft, 2nd is 13ft, 3rd is 16ft prox. Nothing is measured.

H322
3704-3700-3685
3960-3919-3911

VARget
3684-3678-3655
3915-3912-3890
4031-4025-3999

RL-17
3716-xxxx-3651
3826-3807-3784
3942-3927-3893

H4350
3687-3678-3657
3800-3789-3765
3944-3942-3919



I'm fairly comfortable at this point with the chrony's being repeatable within 5fps and accurate within 10fps provided lighting is consistent. It is further my opinion formed over the last year that shooting under artificial lighting gives LOWER as well as more consistent readings. I don't know how much time I'll spend on that quandary but IMO bright sunlight and skyscreens will yield 50-75fps FASTER readings than artificial lighting.

All in all though, surprisingly repeatable to me.

I think I'll keep 'em ;)

Ohh well, back to the old grind...... the guns won't shoot themselves :D

al
 
Alinwa
Henry Childs did a comparison test between a pair of Oehler 43's and a Shooting Chrony or a pair of Shooting Chrony's and one Oehler 43 and it is in the archives from the 1000 yard forum.
In his testing the Chrony or Chrony's were very consistant but off by about 75 fps compared to his Oehler or Oehler's.
In other words if you added or subtracted the 75 fps from all shots it would have been very close to the Oehler or Oehlers.Henry being an engineer didn't look at it like that.He kept saying it should read 3000 fps and not 2925 fps and that you couldn't calibrate it for lack of a better term against an expensive unit and simply correct out the error.
I was at a loss as to why and didn't want to pestor him about his reasoning but if it hasn't been deleted it should still be there.
Waterboy aka Lynn
 
Get the PVM-21. You will get the same readings night or day. No light vs. sunny skies, same readings.

To have a chrono give consistent readings, it HAS to be able to read in any light condition equally, the PVM does just that.
 
Lynn said:
Alinwa
Henry Childs did a comparison test between a pair of Oehler 43's and a Shooting Chrony or a pair of Shooting Chrony's and one Oehler 43 and it is in the archives from the 1000 yard forum.
In his testing the Chrony or Chrony's were very consistant but off by about 75 fps compared to his Oehler or Oehler's.
In other words if you added or subtracted the 75 fps from all shots it would have been very close to the Oehler or Oehlers.Henry being an engineer didn't look at it like that.He kept saying it should read 3000 fps and not 2925 fps and that you couldn't calibrate it for lack of a better term against an expensive unit and simply correct out the error.
I was at a loss as to why and didn't want to pestor him about his reasoning but if it hasn't been deleted it should still be there.
Waterboy aka Lynn
Click to expand...

Thanks Lynn, I'll check but the archives don't go back very far right now.

al
 
Holy moly Al!

4031 out of a 30 cal bullet!

I'd like to see what that did to a coyote.

Wouldn't give them much time to duck.
 
For my purposes

I have cared very little about the speed my crono records as long as I can count on it being consistent. If it lags or is ahead of another make why should that matter, as long as it reads consistent speeds? For that reason I chose the portable cronos withoug big wires, etc, etc. Not as nice perhaps but a heck of a lot easier to use.
 
Pvm-21 VS Chrony???

Really? Accurate in all conditions? Well it should be for 10 times the cost of a chrony.
 
I agree with Pete. I have an old, old Chrony. When I first got it, I proofed it against a couple of the high priced ones (they didn't agree exactly) and it was close enough to suit me and as consistant as the others with its shot to shot readings. So I'm still using it some 20 years later and it's still telling me how fast my bullets are going. One of the best $100.00 I've ever spent. :)
 
Bnhpr said:
Holy moly Al!

4031 out of a 30 cal bullet!

I'd like to see what that did to a coyote.

Wouldn't give them much time to duck.
Click to expand...

It tears coyotes IN HALF, really. Gives whole new meaning to the term 'Red Mist'........ 'Scarlet Rain' more like! :D

It's just another little known 'fun' use for the 300WSM, wicked varminter.

There are vids on youtube. 300WSM does to a 15lb hog what a 22-250 does to a 10oz squirrel!

This rifle platform weighs over 50lb which even makes it pleasant to shoot! :)

Problem is...... any stock Sav or Rem will make the 4000fps and I thought that by going bigger and stiffer with this project I could eke out some more vel...... I was wrong. Cartridges failed at exactly the same pressure level as factory stuff.

I did feel safer though :)

al
 
I've noticed that my PACT gives considerably different readings with and without the glint shields in place, but I can't remember which is higher.

The range I shoot at faces south so the light is fairly constant over the few usually mid-day hours I chronograph, and I have no ability to use artificial lighting there. :( Too soon old and too late smart, or I'd have my own range too.
 
Larry, I put the artificial lighting right on the chronograph and covered it with plastic.... use it rain or shine outside.

This chrono becomes less handy to transport, I keep it in a tote with the lid off.

But it works all the time.

al
 
My Shooter's Chrony consistenly is about 80 fps faster than my Oehler 35. I have beat three other Oehler 35's against mine and they were within 5 fps on all three units. And this was probably due to the fact that they were set way behind mine in a line further from the muzzle.

The Oehler will give consistent numbers day to day regardless of conditions. Sun, clouds, snow on the ground, powerlines, etc. doesn't matter. The only thing it doesn't like is fog. Shuts her down right now.

The Shooter Chrony reads consistently fast but it is also a bit off from day to day and it is WAY more finicky on lighting situations. It won't work on cloudy days but it has fits sometimes with really sunny conditions when the sun is at low angles. It's also fussier about where the bullet passes over the lenses than the Oehler.
 
I have a Shooting Chrony and have problems with the low sun angle during the winter. I have mine mounted on a camera tripod and can tip the chrony in any direction to line up with the sun over the sensors. Mostly because our range faces west, so I just tilt it over about 35 degrees. Works fine that way.
 
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