Is it possible to calibrate a chrony?

Potshot21

Potshot21

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Loaded up and shot some 338 Win Mag loads yesterday with great success! Although I couldn't help but notice that my chronograph registered speeds ~250 fps lower than the reloading manual stated.

I know that there can be variances from the manual to real life, and I would have chalked this up to that, except I've noticed this same amount of discrepancies no matter what rifle I'm shooting. I had the same variation from loading manuals for 45-70, 308 Win, 284 Win, etc. This is leading me to question whether my chrony is out of calibration? Does anyone know how to go about checking your chrony for accuracy?

It is a Shooting Chrony Beta Master I purchased about a year ago. It was a sunny day yesterday, so I was using the hoods.

Hoping I can figure it out so I can get accurate numbers. Thanks for any help!
 
Probably. Bryan Litz did a comparison of various chronographs and found the cheaper ones were less accurate, of course, but the variation in the "absolute" velocity was worse then the variation in shot to shot velocity spread. In other words, you can use them to check your loads for extreme spread/SD, but are less useful for finding your muzzle velocity to enter into a ballistic calculator.

Best route would be to borrow someones Magnetospeed or Labradar, and shoot using it and your chrony simultaneously to find the difference. And use a tape measure when placing your chrony too, so its always the same distance.
 
I'm 99% sure you have to send it back to factory in New York to have it calibrated.

Their pretty sensitive to lighting conditions, might have another go on a scattered cloud kind of day or early morning/evening. Worst thing you can do is shoot when the sun is high, they don't like bright lights.

I'm with Alpheus on ES/SD, the Chrony is consistent. I just verify my dope at distance and true the speed up in my ballistic app to match my impacts
 
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I'm 99% sure you have to send it back to factory in New York to have it calibrated.
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I kind of recall someone mentioning that they have a warehouse/depot in Mississauga.

I compared my Master Beta (tee hee) Chrony with a Magnetospeed and they matched within about 3fps. Which is not to say that they are all that close or that they couldn't be miscalibrated......
 
They are made in Mississauga. On Cawthra Ave.

If you suspect an error, shoot some 22 ammo thru it. It tends to not have a 250 fps error. Standard velocity ammo is usually close to advertised speed.

If one of the screens is tilted out a bit, that will make it read slow.

Have not seen that happen.

I used one once that was not open all the way. All readings were very fast.

I have seen accuracy tests of Chronys. (The maker used to come to the range in my backyard to do his testing. I supplied a variety of calibers to shoot.) In the test 7 Chronys were laid out on a plank with an Ohler in the middle. The biggest error I ever saw was 15 fps.
 
Ganderite said:
They are made in Mississauga. On Cawthra Ave.

If you suspect an error, shoot some 22 ammo thru it. It tends to not have a 250 fps error. Standard velocity ammo is usually close to advertised speed.

If one of the screens is tilted out a bit, that will make it read slow.

Have not seen that happen.

I used one once that was not open all the way. All readings were very fast.

I have seen accuracy tests of Chronys. (The maker used to come to the range in my backyard to do his testing. I supplied a variety of calibers to shoot.) In the test 7 Chronys were laid out on a plank with an Ohler in the middle. The biggest error I ever saw was 15 fps.
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Thanks for the tip Ganderite! I'll bring along my 22 next time I head out to the range and see if it is out.
 
I always bring along a .22 and some standard velocity ammunition (same lot) to check the chronograph before I shoot expensive bullets. This makes sure it is registering the shots, as well as if there are any anomalies in the velocity readings. I often find that reloaded ammunition is not as fast as promised in the manuals.
 
Master Beta Chrony served me well for over 10 years, I'd rather suspect the reloading manual to be imperfect.
As mentioned above, barrel length and actual caliber(s) of the test barrel and yours may differ substantially. Tight barrels shoot faster, sometimes adding 100+fps. Any other variable that effects pressure (bullet seating depth, crimp, geometry of forcing cone, etc., ) also effects muzzle velocity. Temperature, powder burn rate fluctuation between batches, residual oil in bore - you name it! ;)

The only time I had my Chrony to display higher than actual MV (within stated limitation of accuracy) was when I failed to unfold the unit completely (straight) due to interference from tripod adapter.

I like the idea of Standard Velocity .22 test. :)

s>
 
Stranger said:
Master Beta Chrony served me well for over 10 years, I'd rather suspect the reloading manual to be imperfect.
As mentioned above, barrel length and actual caliber(s) of the test barrel and yours may differ substantially. Tight barrels shoot faster, sometimes adding 100+fps. Any other variable that effects pressure (bullet seating depth, crimp, geometry of forcing cone, etc., ) also effects muzzle velocity. Temperature, powder burn rate fluctuation between batches, residual oil in bore - you name it! ;)

The only time I had my Chrony to display higher than actual MV (within stated limitation of accuracy) was when I failed to unfold the unit completely (straight) due to interference from tripod adapter.

I like the idea of Standard Velocity .22 test. :)

s>
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I completely understand the arguement that two rifles are not the same causing differing results. In the case of my 338 WM, the listed barrel length is actually 2 inches shorter than the rifle I was using. This coupled with the fact it is consistent with nearly every reload/rifle shot over it leads me to believe the readings are erroneous.

The 22 idea never dawned on me before, but seems like just the ticket for verification and setup without wasting reloads. The rimfire will be seeing alot more action now!
 
I'll have to try the .22 thing. I almost shot the Nationals with sub Minor loads thanks to my chrony. I double checked my loads on a whim once I got there and had to go buy a case of factory ammo which were pretty hot.
 
I use the Chrony. I have a bunch of them. They left them behind each time they tested.

Here are some things I have noticed.

I know the unit can be incredibly accurate. But I also know I can get less than accurate results...

I only test on an overcast day. I have had bad results in the sun. My units are 15 years old. I am told the newer ones are better in the sun.

I aim at something on the far side of the unit. If I fire at different angles, I can change the speed.

I shoot well back from the unit. 15 feet from a handgun; 20 feet with a rifle. Muzzle blast will cause an error.
 
So I searched the internet for tips and tricks, and there was mention of guys using black foam board or cardboard attached to the sunshade rods to keep the sensors in the shadows.

Anybody have experience with that? Or just wait for an overcast day?
 
I feel the books are optimistic on the speeds. I have yet to see my reload speeds match that of the books. Usually 100 fps lower or in that area.
 
More than once I've finished a range session wondering if the load data with published speeds was screwy or if my chrono was. Every time so far the chrony has proven right in the end.
 
I recently posted a thread about having troubles with my chrony, same thing, low velocity. I always test with a 22 pistol first to check velocities & alignment, but the fact that I'm testing with a 22 pistol and not a rifle means that I probably get a lower-than-standard velocity on my 22 ammo (short barrel). Not sure how much, I'm about 200 fps lower than what is advertised on the box but I'm shooting it from a min. barrel length pistol not an 18"+ rifle barrel. I should bring one of my 22 rifles next time and see where it sits.
 
Potshot21 said:
So I searched the internet for tips and tricks, and there was mention of guys using black foam board or cardboard attached to the sunshade rods to keep the sensors in the shadows.

Anybody have experience with that? Or just wait for an overcast day?
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The sensors look up and see the shadow of the bullet passing overhead. A black foam or cardboard would probably not work. What would work is a sheet of white translucent plastic. You could have a large sheet covering the entire unit or two pieces, one over each screen.

For the latter I would try the plastic from a milk jug or a winter washer fluid jug.

I have tried a large sheet. On a windy day it won't stay in place and it is really important to keep well back so the muzzle blast does not knock over the unit.

If you want to fire a 22 standard velocity round first, to make sure the unit is operational, leave the box of ammo in the unit. That way you have the ammo and it is always the same.

I also have a spare battery taped in there.
 
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Potshot21 said:
So I searched the internet for tips and tricks, and there was mention of guys using black foam board or cardboard attached to the sunshade rods to keep the sensors in the shadows.

Anybody have experience with that? Or just wait for an overcast day?
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My crony came with plastic shades made especially for shiny days. They are pretty much like Ganderite describes: white translucent, a bit less opaque than milk jug plastic. As long as some light can get through and it is diffused, you should be good. Shouldn't change the measured velocity though.
 
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