Oehler 35P vs Shooting Chrony

[bobinpa]

Hi guys... I ran 2 chronographs today. A Chrony Gamma with an Oehler 35P right behind it. The results were shocking. The Gamma was way different than the 35P. As much as 358FPS faster than the 35P.
I had brand new batteries in each.
Batteries came out of the same package.
The Gamma was approx 6' from the muzzle and 35P was immediately behind it.
The sunlight was the same on each and I had the sky screens on each.
The smallest difference between the 2 was 18 FPS

Is the Gamma that bad or is there a problem with it? (In your opinion)
What gives?

 

[Dusty Stevens]

Its that bad

 

[spclark]

6’ is too close... 10’s better or 15 if you’re patient and willing to take the time it demands to do the lining up.

At less than 10’ you’re reading muzzle blast along with your projectile with most optical chronos.

That’s why LabRadar and Magnetospeed have done so well in that regard, or that two-mic thing The Kid who came up with the ShotMarker & AutoThrower came up with for his next act: little need to line them up as carefully for results you can accept.

The “you get what you pay for” maxim still applies.

I started with a red fold-up Chrony, went through a few brittle sky screens and lots of frustration over different lighting conditions before I bought a 35P. I still have both; guess which gets used most often.

 

[Charlie-NY]

I ran a Chrony directly behind my new Oehler 35P. There was a fairly consistent 100 ft/sec difference with the Chrony reading faster. I called Oehler who was good enough to say "send it back and we'll test it for you". I boxed everything up, including my screens, and shipped it back.
A week later Oehler called. They said that it's "almost" impossible for it to read incorrectly with the proof screen verifying the primary screen but they bench tested it anyway. The chronograph bench tested fine and they subsequently did a firing test using lab grade ammo with a known velocity. The chronograph was reading very accurately.

I got rid of the Chrony.

 

[waltk]

I recently purchased a ProChrono by Competition Electronics Inc. This is the Bluetooth model which is wireless and reads out on your smartphone. I had the complete opposite results. I set the ProChrono in front appox. 10 to 12 feet from the muzzle of my 9mm 1911. Directly behind it was my Oehler 35P set on a 4 foot spacing bar. The results were surprising. Ninety five percent of the time the readings were within one or two fps. Very occasionally the reading might be ten or twenty fps off. The ProChrono is small, short, light weight, fast and easy to set up. For the money, if you shop around about $125.oo or less.
I am not affiliated with this company. Highly recommended.

 

[Liven The Dream]

Well about 28 years ago we did this same Test in Illinois at the State Range .
Not one person at the Range would believe the Results.
The 35 was 10ths above across the board 3 times of the $56 Chrony .

 

[Straightshooter1]

A few years back I read an article about where a test was done for a number of chronographs to see how accurate they were compared to one of the high end scientific equipment that produces very accurate readings. What stood out to me and as I remember, the Oehler the used was the best and surprisingly (to me, anyway) the MagnetoSpeed was a close second. The other chrono's were substantially back that I was convinced to go with the MagnetoSpeed.

Before the MagnetoSpeed I had a ProChrono and so when I got my MagnetoSpeed I wanted to see what the difference was so I might better interpolate all the chrono data I had collected from my ProChrono. So, set them up together with the ProChrono ~15 ft. from the muzzle and used my .308 with the MaagnetoSpeed mounted on it. Accounting for the velocity different at the muzzle and 15 ft away, I was surprised that the ProChrono readings were more accurate that I anticipated . . . like 5-10 fps difference and, the readings were close in parallel to the MagnetoSpeed which one can see if a graph was draws of the two units data.

Addendum: I forget to mention that the LabRadar was was part of the test too and it's accuracy was only slightly better than the MagnetoSpeed and the LabRadar does provide a lot more data, like down range velocities.

Based on this anecdotal evidence in my experience, the ProChrono is really a good value and does a good job in the same way a comparator tool does. But, I do feel that for accuracy sake the MagnetoSpeed or the more expensive Oehler is the way to go.

 

[McFred]

When I "upgraded" to my 35P I ran my $99 Shootin' Chrony in-line for a back-to-back comparison (approx. 3.5m from the muzzle). Virtually no difference in readings, fast or slow. FWIW the 35P sucks to set up in the wind. If was attached to a boat I could go sailing. If I were to do it all over again, I'd consider the Magnetospeed. There are more than a few times I've wanted to blow the 35P off its stand and shoot it again just to be sure it's real dead.

So long as your "discount" optical chronny reads consistently, you can always space out the sensors to "calibrate" it with a "better" chronny.

 

[bobinpa]

Thanks for the info guys. Looks like the 35p is my new go to chrony. I appreciate the help.

 

[Dusty Stevens]

I havent pulled out a 35p since the labradar came out. Dont know of many that has

 

[David101]

I have always wondered why there were never any upgrades made to the Oehler. After reading the specs and the principle of operation I was surpised to find that the internal oscilator speed was so slow. Nearly all oscillators used in electronic frequency counters are 10 Mhz and you can even buy complete oven contolled oscillator packages off the shelf for use in such items. One of those used in the Oehler would have given an order of magnitude extra resolution and the higher stability and less drift in the oscillator would have given better accuracy and consistency in readings over time.

 

[McFred]

I havent pulled out a 35p since the labradar came out. Dont know of many that has

Europeans who shoot .17s and .20s. They only get the low-watt radar. I gather the small projectiles are hard to detect.

I have always wondered why there were never any [oscillator] upgrades made to the Oehler.

Maybe there's no need? Diminishing returns? You can set the DIP switches for a 12' spacing to get more resolution. Discrete components are easy to maintain. If it's all integrated and when something fails it all goes in the trash heap. Maybe high tolerance oscillators are expensive?

I'm fine with the electronics capturing velocity, however a lot of hardware/power/data management and packaging could be improved. I don't know who their target market is though. I admit the 9v battery from 1950 was frequently a point of frustration for me. I've got a huge lithium I plug mine into now.

 

[Fuj]

I havent pulled out a 35p since the labradar came out. Dont know of many that has

Lab user here, and I used to use an ol' 33 !!

 

[Rick300]

Lab user here, and I used to use an ol' 33 !!

I still use my 33! Extremely reliable. Reminds me of the old Texas Instruments calculators back in the day

 

[INTJ]

The issue with any of these chronos isn't accuracy. It's not had to make accurate timers. The issues are triggering and validation. The 35P and the Labradar measure the velocity more than once per shot, so there is a built in double check which may be a slight advantage.

Many years ago I put a ProChrono in front of a 35. When corrected for distance, the average of the five shot string was 5 fps though individual shots varied by as much as 20 fps.

Like many I have had several chronographs over the years. A Beta Chrony, a ProChrono, an Oehler 35, a CED Millennium II, an Oehler 35P, and a Lab Radar--in that order. All of them were accurate enough.

The Beta Chrony was fussy about light conditions as was the CED. The Oehlers were very reliable but a little slow to set up. All of these required shutting down the range to setup.

The Magneto speed was always a non-starter for me as I do all load development with a chrono and attaching the Magnetospeed can affect barrel harmonics.

Four or Five years ago I replaced my 35P with the LabRadar and haven't looked back. Where I shoot now is on a raised berm so the 35P can't be set up unless I had 10' high stands. That said, once set up I think the 35P is the most reliable in terms of triggering, though once you figure it out the LabRadar has no issues.

Overall I would rank the ones I used as:

1. LabRadar
2. Oehler
3. ProChrono
4. CED
5. Beta Chrony