Chronny
- Thread starter Ian Robertson
- Start date
Is that a polite way of saying they don't work well?
Ian, I'd recommend placing the Chrony chrony lovingly on a shelf, and leaving it there until it has collected adequate dust to relieve any guilt you may feel when cannibalizing it for parts to make other, more useful projects, or sell for scrap value.
Reason is, is that similar to what BAM is alluding to, the hardware/ software combo in the Chrony is unacceptable for its intended application. The published aquisition specs available for the unit says it's reliable to measure V0 to only 99.5% accuracy. You can determine from that value what the quality of the all-holy "SD" is going to be. In short, for the SD numbers that 'accuracy minded' folks worship regularly when trying to eek out skinnier pokey through the paper dispersion, the Chrony yields garbage at best, taken for gold by many. Say your V0 was 2800 ft/s, the unit's measurement accuracy is Vmeasured +/- 14 ft/s (0.5%). Consider that over a ten shot spread, that each V value is independently accurate to 14 ft/s (+/-0.5%), but the unit's SD output value for the set was 10 ft/s (ie +/- 0.35% of Va=2800) Do those numbers seem questionable? I think so too. However, I could also misunderstand statistics. I would suggest, though, that if every shot was in fact, exactly 2800 ft/s, the best you could do is establish what the machine's SD of measuring error is, and potentially come back to verifying that V0=2800. But asking for the uncertainty of uncertainty will certainly produce uncertain results, and in turn, produce certain confusion. I bet it would break hearts to mention that a Chrony chrony saying "congratulations, your SD for those last five shots was 7!" is merely a statistical event. Would shooting thru three Chrony chrony's be three times better, three times more confusing, or just three times more expensive?
For worthwhile measurements, one of the best systems out there today is Magnetospeed. It's convenient, easy to use, and claimed accurate to 0.1%- good enough. I've used one, and it's excellent. It does yield half decent statistical results output, for those interested in such things. Now, many jump on the 'what about barrel harmonics!' wagon- which the logic behind is valid, but to continue the argument is short sighted. If the barrel goes out of node when the bayonet is removed, then it may be returned to node by either changing the charge slightly, or adding 5.3 oz of weight to the end of the barrel. I think that I would rather have the slight inconvenience of dealing with harmonics than pay for a roulette wheel of a data machine which hinders as much progress as it supports. Labradar has similar accuracy claims, but whether a unit sees the light of day in public is yet to be seen. That, and I know that I would not be a fan of having my guts getting cooked by buddy's unit on the next table while he's convinced that he's going to out fox the manufacturer's G7 numbers on the bullet he's in love with by labradar-ing ten shots at 5 yards and ten shots at 95 yards, before using his new found G7 data that is .003 more or less than published and 'stretch its legs' at 300 yards, or be any more accurate at 3/5 of a mile because his measured BC is 1% more better.
Good luck with your choice- and thank you for a post question that I didn't answer at all, but it did inspire some entertaining and informative research!
Ian, I'd recommend placing the Chrony chrony lovingly on a shelf, and leaving it there until it has collected adequate dust to relieve any guilt you may feel when cannibalizing it for parts to make other, more useful projects, or sell for scrap value.
Reason is, is that similar to what BAM is alluding to, the hardware/ software combo in the Chrony is unacceptable for its intended application. The published aquisition specs available for the unit says it's reliable to measure V0 to only 99.5% accuracy. You can determine from that value what the quality of the all-holy "SD" is going to be. In short, for the SD numbers that 'accuracy minded' folks worship regularly when trying to eek out skinnier pokey through the paper dispersion, the Chrony yields garbage at best, taken for gold by many. Say your V0 was 2800 ft/s, the unit's measurement accuracy is Vmeasured +/- 14 ft/s (0.5%). Consider that over a ten shot spread, that each V value is independently accurate to 14 ft/s (+/-0.5%), but the unit's SD output value for the set was 10 ft/s (ie +/- 0.35% of Va=2800) Do those numbers seem questionable? I think so too. However, I could also misunderstand statistics. I would suggest, though, that if every shot was in fact, exactly 2800 ft/s, the best you could do is establish what the machine's SD of measuring error is, and potentially come back to verifying that V0=2800. But asking for the uncertainty of uncertainty will certainly produce uncertain results, and in turn, produce certain confusion. I bet it would break hearts to mention that a Chrony chrony saying "congratulations, your SD for those last five shots was 7!" is merely a statistical event. Would shooting thru three Chrony chrony's be three times better, three times more confusing, or just three times more expensive?
For worthwhile measurements, one of the best systems out there today is Magnetospeed. It's convenient, easy to use, and claimed accurate to 0.1%- good enough. I've used one, and it's excellent. It does yield half decent statistical results output, for those interested in such things. Now, many jump on the 'what about barrel harmonics!' wagon- which the logic behind is valid, but to continue the argument is short sighted. If the barrel goes out of node when the bayonet is removed, then it may be returned to node by either changing the charge slightly, or adding 5.3 oz of weight to the end of the barrel. I think that I would rather have the slight inconvenience of dealing with harmonics than pay for a roulette wheel of a data machine which hinders as much progress as it supports. Labradar has similar accuracy claims, but whether a unit sees the light of day in public is yet to be seen. That, and I know that I would not be a fan of having my guts getting cooked by buddy's unit on the next table while he's convinced that he's going to out fox the manufacturer's G7 numbers on the bullet he's in love with by labradar-ing ten shots at 5 yards and ten shots at 95 yards, before using his new found G7 data that is .003 more or less than published and 'stretch its legs' at 300 yards, or be any more accurate at 3/5 of a mile because his measured BC is 1% more better.
Good luck with your choice- and thank you for a post question that I didn't answer at all, but it did inspire some entertaining and informative research!
just having some fun
CGN Ultra frequent flyer
Here is the instructions
ht tp://www.shootingchrony.com/manual_BG.htm
Aim high or you will need a new one
the shootingchrony is ok just rember the pen and paper to write everything down as after all these years you still can't hook it to your computer
ht tp://www.shootingchrony.com/manual_BG.htm
Aim high or you will need a new one
the shootingchrony is ok just rember the pen and paper to write everything down as after all these years you still can't hook it to your computer
I just retired my chrony in favour of the new Steiner Superchrono
http://www.steinertsensingsystems.com/product/superchrono-std/
Tested it last weekend in at the Swiss range at Homestead. My chrony beta was indicating 400 FPS faster than possible with factory match ammo. Setup was a breeze.... Unzip the padded cover, aim it at the target, turn on, shoot. I think it is about $500-550 in Calgary at CSC.
http://www.steinertsensingsystems.com/product/superchrono-std/
Tested it last weekend in at the Swiss range at Homestead. My chrony beta was indicating 400 FPS faster than possible with factory match ammo. Setup was a breeze.... Unzip the padded cover, aim it at the target, turn on, shoot. I think it is about $500-550 in Calgary at CSC.
Actually as long as you don't get the err the average speed of several units is more accurate than any one.
The biggest problem with "cheap" chronoraghs are their accuracy is barely within 30 fps and that varies with lighting and alignment of the planets. So how do you get a more precise reading?
Answer is siple... spend more money right.
When you do spend more money (prior to the new doplar style systems) you will get an elaborate multi shield version and it will be about 10 feet long.
So why does this long multi sensor version provide a more accurate reading?
Answer is simple...
The farther apart the sensors are, the less of a percentage of variation. Twice as far apart is by default twice as accurate.
In addition they run multiple shields... (usually three) why would they do that?
Answer is not simply redundancy... its so they can average the results of all - even if the user is not aware that is what is happening in the device firmware.
It would not be an unreasonable experiment to double or even triple the distance between the sensors on a chrony. The result would be a read out speed equal to one third of reality, but it would be a more accurate number... percentage wise, and more indicative of the actual shot to shot speed variation. Just remember to triple the readout to know the actual speed.
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The Steiner is a similar idea to Silver Mountain Targets (made in Canada facebook.com/electronictargets) which uses a sensor in each corner of the target to triangulate the position and then averages the four to show position and score on a wifi device. It also gives velocity at the target for each shot. Any target can be made to work with this system, anything from a fig 11 to a 1000yd ICFRA target.
I have pretty much given up on my Chrony. The only time it worked flawlessly was in fog where you could barely see the targets at 100yds. Maybe if it was enclosed in some sort of fabric bag with only a hole to shoot through?
I have pretty much given up on my Chrony. The only time it worked flawlessly was in fog where you could barely see the targets at 100yds. Maybe if it was enclosed in some sort of fabric bag with only a hole to shoot through?
There's this one too, whenever they become available...
http://www.mylabradar.com/
Regardless of convenience, the question still remains....
What is the true accuracy level of these various chronographing systems?
To get single digit SD you need a chronographing system that has a deviation of less that 1 FPS.
This model is supposedly less than 0.1 percent which is 3 FPS @ 3000 FPS
http://www.mylabradar.com/
Regardless of convenience, the question still remains....
What is the true accuracy level of these various chronographing systems?
To get single digit SD you need a chronographing system that has a deviation of less that 1 FPS.
This model is supposedly less than 0.1 percent which is 3 FPS @ 3000 FPS
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Good to know these work well. I picked up a used Oehler but need to get about a ten foot rod to use with it. I need to get over to a machine shop and get one made that unscrews into two or three sections so I can fit the damn thing in my vehicle.
rnbra-shooter
CGN Ultra frequent flyer
- Location
- New Brunswick
Nahh, your chrono doesn't have to be *THAT* much better than your ammo.
If by "single digit SD" you mean your ammo has SDs of 6-9fps, you can measure that if your chrono has an SD of ~3fps. Basically the idea is that you can tolerate *SOME* error in your measuring equipment (chrono), so long as *MOST* of the error is in the thing being measured (actual speed of the bullet)
Glock4ever
CGN Ultra frequent flyer
- Location
- Edmonton, AB
Don't know where all of the hate for Chrony comes from, I have used one for a long time (>10 years) and it does what it supposed to for a home brewer - i.e. give you enough information about MVs to produce predict data to develop a ballistic chart for your ammo and rifle. If you want to go out and buy a high end chrony to brag, fill yer boots but don't kid yourself that shooting over a more "accurate" or "precise" device is going to tell you anything more than a basic chrony will. If you actually look at the article and look at the raw data charts on the enclosed article, you will see that the Chrony's data isn't far off from the test chrony (Oehler 12 ft). As somebody who has visited a proper ballistic lab setups in the USA and Canada, you aren't any where near the controlled conditions required to get precise data on your loads and buying a slightly more accurate chrongraph isn't going to change that.
As an example, you set up your chrony on a nice sunny day and shoot your 5 or 10 round group at a target and get a string of velocities. There may be some variations - is it guaranteed that the data is wrong (or maybe its right?) because of the chronograph? Maybe you were careless and left the rounds in the sun and they slowly heated up as the sun rose or cooled down as a cloud cover rolled in. Maybe the chronograph is wrong but just maybe you didn't keep your ammo at the right temp. Maybe you didn't let your barrel cool down enough between shots (you are measuring barrel temp right?) There are a plethora of problems shooting outside with a chronograph that could result in "bad data" before you could even come close to blaming the measuring instrument.
As well, I do find it amusing that there is so much focus on Standard Deviation. I get the sense that some folks here don't truly understand statistics and would like to sound smarter than they actually are... SD is only useful if you fire a large amount of rounds to build a proper distribution and you need to keep in mind that it is only good for a specfic set of conditions. Most folks I see shoot maybe 5 rounds over a chrony and if they are really interested maybe 10 rounds at a given temperature. This really doesn't tell you much about your ammunition except that it produces a rough (and I mean rough) average velocity for a given outside temperature and humidity. If you are serious about getting ballistic data than you need to shoot in a variety of conditions and larger sample sizes so that you can extrapolate some useful information about your ammo. Just my 2 bucks on chronographs.
As an example, you set up your chrony on a nice sunny day and shoot your 5 or 10 round group at a target and get a string of velocities. There may be some variations - is it guaranteed that the data is wrong (or maybe its right?) because of the chronograph? Maybe you were careless and left the rounds in the sun and they slowly heated up as the sun rose or cooled down as a cloud cover rolled in. Maybe the chronograph is wrong but just maybe you didn't keep your ammo at the right temp. Maybe you didn't let your barrel cool down enough between shots (you are measuring barrel temp right?) There are a plethora of problems shooting outside with a chronograph that could result in "bad data" before you could even come close to blaming the measuring instrument.
As well, I do find it amusing that there is so much focus on Standard Deviation. I get the sense that some folks here don't truly understand statistics and would like to sound smarter than they actually are... SD is only useful if you fire a large amount of rounds to build a proper distribution and you need to keep in mind that it is only good for a specfic set of conditions. Most folks I see shoot maybe 5 rounds over a chrony and if they are really interested maybe 10 rounds at a given temperature. This really doesn't tell you much about your ammunition except that it produces a rough (and I mean rough) average velocity for a given outside temperature and humidity. If you are serious about getting ballistic data than you need to shoot in a variety of conditions and larger sample sizes so that you can extrapolate some useful information about your ammo. Just my 2 bucks on chronographs.
My only real problem with the chrony is to get it to read every shot. I have read and followed the instructions to no avail. I am going to try putting the entire unit in white garbage bag to simulate foggy conditions under which it worked perfectly.
Glock4ever
CGN Ultra frequent flyer
- Location
- Edmonton, AB
Ian: I have never had a problem with mine. They do have a smaller reading/shooting zone compared to some of the other chronographs but it is because the unit is so small. What I do is I have mine mounted on a Tripod that has a crank handle elevation (paid like 30 bucks at Walmart for it). When I set up to test for velocity, I first set up the bench and rifle so that everything is lined up on target. Next I then put the chronograph in front of the muzzle about a yard away and crank the elevation so that the brass portion of the connector rods are in line with the muzzle (elevation wise). I then shoot groups and I have never had an issue with the sensor missing the bullet's travel or the err msg. On cloudy days you can macgyver up a flashlight and gun tape to brighten up the white reflector but I have never had this real issue as I generally don't shoot in rainy/heavy overcast conditions because the wind and rain can really screw with your results. I also really like the fact that Chrony will replace or trade in your chrony if you accidently shoot it. IRAQVETERAN8888 on youtube does a comparison of the F-1 Chrony to the Oehler chronograph and he shows the setup of the Chrony very well and has an excellent illustration of the reading zone that I am trying so poorly to convey. Once you see how he sets it up you shouldn't have any issues with yours. If you continue to have problems with yours I would send it back to them for servicing because it sounds like it may be malfunctining. They have a warranty center in Ontario which is great for product support. BTW here is the video I was talking about:
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