Most accurate chronograph?

rimfiremac

rimfiremac

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What is the accuracy of the most accurate chronograph available today?

Is there real interest in being able to measure to +/- 2 fps, or are people usually happy seeing their $500 machine with an 0.5% measurement error tell them that their SD is in the single digits, even when their measurement error exceeds that?
 
I can't answer your question but I think an Oehler 35P with the 3 screens set at 4 feet and 8 feet would be as accurate as you would ever need for sporting purposes. The bullet is measured twice and computer compared as to whether the screen triggering was accurate. Some shiny bullets can cause a false triggering with light refection. Those false readings are marked...
 
This might be the best chronograph out there hope to be test it against a old but very reliable Oehler 3 screen 35 model. The 35 has been a stand by unit for many top shooters and US military. Problem with Oehler is set up time very big and awkward unit.
Peter Dobson of Hirsch Precision is Canadian distributor and has them in stock



PVM-21 Infrared Chronograph
Oehler's phasing-out of its Model 35 chronograph line has left a void in the market for high-grade chronographs. The new PVM-21 chronograph from Germany will fill that need. It has many advanced features and comes packaged with very sophisticated software.

This might be the best chronograph out there hope to be test

With the PVM-21, which employs multiple infrared emitters, you can use the chrono in any light condition--indoors or outdoors. Tests of two PVMs set in parallel proved the units give extremely consistent results. Measuring a 55-grain .223-caliber bullet, two units showed an average variance of less than 1.5 fps on the shot by shot readings. Compared to an Oehler, the front and rear light sensors are placed fairly close together. With conventional engineering, longer spacing normally produces more accurate and reliable results. However, the PVM-21 employs a very high measuring frequency (16.0 Mhz) to provide excellent results even with compact dimensions. Additionally, the unit samples ambient light every 10 seconds allowing it to automatically adjust to changing light conditions. The PVM-21 features a 250-shot memory, and full PC-compatibilty via USB interface. Output can be displayed on a laptop PC, as well as the LCD readout on the PVM-21's display unit.
 
peterdobson said:
Some of the Kurzzeit chronos are accurate to .05m@1000 m/s.
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At what cost and effort is this achieved?

Would a system that could be attached to the end of a barrel and measure to +/- 2 fps intrinsic to the bullet velocity itself come off as 'too good to be true'?

edited to add... Performance would be based off sampling rate, of course.
 
Even the PVM, just looking at the site, claims accuracy within less than 1%. So on the basis of 3000fps, that's 30 fps at 1%, 15 fps at 0.5%, and 7 fps at 0.25%- with a 7fps intrinsic error, how are SD values even close to reliable? Or does the whole notion of chrono based SD's exist merely for our psychological comfort that 'the load' does actually shoot; after all, the target doesn't lie at the end of the day.
 
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rimfiremac said:
Even the PVM, just looking at the site, claims accuracy within less than 1%. So on the basis of 3000fps, that's 30 fps at 1%, 15 fps at 0.5%, and 7 fps at 0.25%- with a 7fps intrinsic error, how are SD values even close to reliable? Or does the whole notion of chrono based SD's exist merely for our psychological comfort that 'the load' does actually shoot; after all, the target doesn't lie at the end of the day.
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It depends on what you need your chronograph for. For many applications, we are interested more in precision than in accuracy.

For example, a chrono might be accurate to within 2% - it might say that my 3000fps bullet is going 2940fps. So my calculation of the amount of elevation needed at 900m will be wrong (27.1 MOA above my 100m zero is the correct value, 28.5 MOA above my 100m zero would be the value inferred from the 2%-inaccurate reading)

The same chrono might be precise to 0.2% (a precision of 6fps for a 3000fps measurement). If I am interested in establishing whether my ammo is *uniform*, I need to *precisely* (not *accurately*) measure the muzzle velocity. A 6fps precision (and 60fps inaccuracy) would allow me to determine that batch1 of my ammo (SD=10fps, ES~30fps) is better than batch2 of my ammo (SD=15fps, ES~45fps).
 
rnbra-shooter said:
It depends on what you need your chronograph for. For many applications, we are interested more in precision than in accuracy.

For example, a chrono might be accurate to within 2% - it might say that my 3000fps bullet is going 2940fps. So my calculation of the amount of elevation needed at 900m will be wrong (27.1 MOA above my 100m zero is the correct value, 28.5 MOA above my 100m zero would be the value inferred from the 2%-inaccurate reading)

The same chrono might be precise to 0.2% (a precision of 6fps for a 3000fps measurement). If I am interested in establishing whether my ammo is *uniform*, I need to *precisely* (not *accurately*) measure the muzzle velocity. A 6fps precision (and 60fps inaccuracy) would allow me to determine that batch1 of my ammo (SD=10fps, ES~30fps) is better than batch2 of my ammo (SD=15fps, ES~45fps).
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My issue in logic comes from the uncertainty that if the claimed accuracy is 1%, data from each shot may be in error from reality by that 1% (substitute 0.5% for actual performance and the numbers still are concerning). It just appears to me there may be a 'garbage in garbage out' scenario. In essence, that 1% might deal with the precision of the unit exactly. Thinking about how the chrono system and software works, the number which is always suspect to error is the calculated velocity of each projectile. After that, very little error enters the system through calculation. Incidentally that particular number subject to error is a criticality in the system.

Just maintaining the skeptical viewpoint... we obviously find loads that work, and use chrono's to help validate results, but I'm not certain that the results we take as reliable are so with current technology.

Thanks for coming out noneck :wave:
 
Another error/variable in results appears to be how the rifle is held, so to get more accurate readings one should really shoot from a really solid bench/sled, rifle really strapped in, with no human error. This should both help get a closer reading if you eliminate recoil, and give more repeatability, but at the same time does not represent how it will be shot in the field where you have to re-introduce those error factors, making the whole exercise probably pointless beyond scientific reasons.

I've not yet found a chorograph stating a repeatability spec. To me that is a problem, which makes me wonder if their accuracy is purely theoretical.
 
so if the margin for error is .5% so at 3000fps that's 15fps, but I don't think that it will vary that much shot to shot,

what I think they mean is more of a calibration margin of error, so you could still have a low SD that is correct, but all of your data might be 15fps faster or slower then what its reading

the only thing that will mess-up your SD is if your light conditions are varying shot to shot

I don't know if that made sense, but that's how I understood it

Alex
 
Has anyone looked at the MagnetoSpeed chronograph? It clamps to the end of your rifle and is getting some very good reviews. So far its the best idea I have seen yet and lighting conditions have no affect on your readings. Accuracy seems amazing. I'm seriously thinking this is the way I will go
 
The P-35 is my third chrono (2 first ones were Chrony ) and the last one, i will ever buy, it is just great and simply among the best... JP.
 
Here's a test of several brands of chronographs conducted on another site:

We tested all the major brands.

1. Shooting Chrony -- Narrow sweet spot. Controls are confusing -- multiple pushes of same button required. Some units are very fussy as to light conditions. No IR option. Good Battery life.

2. PACT -- IR option doesn't work very well. Too many buttons on keypad. Thermo printer burns batteries quickly. We had to send one unit back. Having printer is nice, but overall, battery life is big issue.

3. Oehler 35P. Big, heavy with proof channel. Base unit very simple to use and very reliable. Sensors have proper lenses so the beam is focused, giving bigger sweet spot. Paper is very hard to feed when you run out. Battery life is pretty good considering it has a printer.

4. CED -- Small, light keypad. Nice big display. Keypad is pretty intuitive. Hinged sensor mounting bar is clever, compact when stored, but you have to be careful to slip the sensor bases on securely. IR option works good, IF you have the plugs seated tightly.

5. PVM-21 -- Once assembled (like a box kite), it is very fast, easy to set up. IR emitters work fantastic -- it will register lead pellets in complete darkness. AC adapter is funky. Unit works better with 12V battery but that has to be carried separately. Very reliable unit if you just use the white receiver box, but then you have to write down the results. Software is cranky to install and Not at all intuitive. Most guys using PVMs have given up on using with a lap-top. Unit desperately needs a better (less buggy and simpler) software interface, and it should be converted to run 5.5 volts so you could power from your laptop.

What would I buy? CED for entry level. Oehler if you have the money. PVM-21 if you shoot in low-light. PVM is excellent, but the computer interface is "not ready for prime time" and far too complex for most users. We had issues just installing the software on laptops -- you have to fiddle around to get the drivers to "take". If PVM would plug directly into USB port (like a printer) with clean software, it would be my choice for field assignments.

I have a CED M2 with the infra-red option. I'm quite satisfied with it except that, Like other optical chronographs, set up is a PITA, particularly when the range is busy. I just bought a Magnetospeed for those situations and I'm very happy with its reliability. I intend to compare it to my CED M2 IR and a friend's Oehler P35 this Spring.
 
SND said:
Another error/variable in results appears to be how the rifle is held, so to get more accurate readings one should really shoot from a really solid bench/sled, rifle really strapped in, with no human error.
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I have heard that (that the muzzle velocity is affected by whether you hold the rifle firmly or whether it is free to recoil). While I didn't do a proper scientific experiment, I was very interested in testing at the time, and I tried to see if I could measure the effect. I wasn't able to see it.

Another thing I had heard is that cheek pressure and/or butt plate pressure affected the point of impact of shots at 1000 yards. As far as I could tell, I could never see an effect. This was using a rifle that shot approx. 1.25 MOA groups (10-15 shots) at 1000 yards.

I've not yet found a chorograph stating a repeatability spec. To me that is a problem, which makes me wonder if their accuracy is purely theoretical.
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Yep. As soon as you actually start to care, and have a look at these things, it seems that the manufacturers are pretty clueless about what their measuring equipment can/cannot do.
 
As soon as you actually start to care, and have a look at these things, it seems that the manufacturers are pretty clueless about what their measuring equipment can/cannot do.

Does it really matter? Most of the most accurate rifles in the world have never shot through a chronograph.
 
Would not be caught witout my P-35, the Nemesis shoot tru it all the time even with my proven load, all shots are registered... JP.
 
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