Statistics- what does and doesnt matter.
- Thread starter BradY
- Start date
That is like saying “I don’t care what the headspace gauge says, I just only care if it goes bang!â€. Things that helps you understand why you did not reach your goal is always useful….
People might be surprise to hear that I am not a lover of statistics since I am lousy at it, but hey it’s a tool and if it helps me get from x to y, I use it instead of banging my head against the wall – that I know does not work. LOL!
People might be surprise to hear that I am not a lover of statistics since I am lousy at it, but hey it’s a tool and if it helps me get from x to y, I use it instead of banging my head against the wall – that I know does not work. LOL!
[br]jlow said:
Oehler chronos are good but are a dated design with a low sampling rate. My PVM-21 is fairly accurate for a consumer grade chrono. It uses an infrared LED "light "curtain", providing excellent triggering response in any light. It has four times the sampling rate of an Oehler and the screen frame fixes the spacing. Granted, it is expensive. But, it is the best available short of much more expensive commercial units. FWIW, Lapua chose the Kurzzeit system for their Mesa Service Center when they could have chosen just about any other system. Regardless of the approach you choose to take, good results start with good data.
sleepygator said:
Wise words. Good data followed by good analysis yields good results. Thanks, I wish I could be as pithy. Regards JCS
CatShooter
sleepygator said:
With an Oehler, the sampling rate will allow a 0.10" accuracy - the PVM-21 allows a 0.025"... but there are several issues - the spacing on the PVM is ~1 foot, the Oehler is 2 to 8 feet (for those that need the accuracy), so when pushed, the Oehler will deliver more accurate results.
But the other more real problem is that the sensors on both machines are the limiting factor. The optical pickups can not trigger on a bullet shadow with that accuracy.
So in the end, nno matter which you own and how much you spend, you are only close... not exact.
[br]CatShooter said:
No, it is still less accurate because of the "fuzzy" triggering Oehler uses. Diffuse light will never provide the repeatability of a focused LED and full-time infrared. Kurzzeit made their reputation developing triggering devices, mostly associated with high speed photography. The screens may also be adjusted to better tailor the event duration for a specific caliber. That said: I've owned and used Oehler chronographs and had no complaint other than the lack of a digital interface. [br]
No system will ever provide an exact speed, but some are more accurate than others. In the Kurzzeit case, it has both accuracy and an effective digital interface for my needs. If someone else chooses a different approach, that does not make them wrong. They may have different requirements.
The simple truth is none of us can afford the commercial grade units, so it comes down to what will do the job. For me, the Oehler does well enough most of the time to get the job done which means reproducible MVs and a way to check for bad data. So as you say good results starts with good data….
The Oehler’s weakness is that it requires light which I sometimes have problems with at the old place I shoot at because in their infinite wisdom, they build something like a multi-level arbor like setup in front of the firing line to block aberrant bullets. The trouble with this is it blocks enough light to cause trouble. Thank God I am now shooting at a new range which does not have this problem.
The PVM-21 looks like a nice unit although really only slightly more expensive than the Oehler. The specs looks good but my question is have you found any problems with it because I frequently find book vs. real life does not translate.
The Oehler’s weakness is that it requires light which I sometimes have problems with at the old place I shoot at because in their infinite wisdom, they build something like a multi-level arbor like setup in front of the firing line to block aberrant bullets. The trouble with this is it blocks enough light to cause trouble. Thank God I am now shooting at a new range which does not have this problem.
The PVM-21 looks like a nice unit although really only slightly more expensive than the Oehler. The specs looks good but my question is have you found any problems with it because I frequently find book vs. real life does not translate.
[br]jlow said:
Good - [br]
Accurate, dependable, and easy to use. Supplied software has a report print capability that I customized to dump a format Excel can read. Completely light independent. Large (4.4" X 7.8") active area. There is an alleged interface to QuickLOAD that I have never tried. [br]
Bad - [br]
Supplied 12V battery died after a year. I replaced it with an alarm battery with three times the amp/hour rating and no problems since. The screens act like a big sail and tripod must be weighted. Ask me how I know.
Interface is not very conducive to doing anything at the range. Fine for dumping data to analyze as described, not much else. It does have a display and it's easy to see each shot's velocity.Thanks for the interesting info! It does look like a good unit, and at least to me, the biggest draw would be the light independence for the reason I mentioned.
I can’t really complain as I count myself lucky to have the Oehler and I got it for a great price from a friend and with my own 2’ to 4’ upgrade, it has served me well. The wind thing is the same with the Oehler except worse – LOL!
I can’t really complain as I count myself lucky to have the Oehler and I got it for a great price from a friend and with my own 2’ to 4’ upgrade, it has served me well. The wind thing is the same with the Oehler except worse – LOL!
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