Another chrony question

[deadon]

I finally found my chronograph. All I remembered about it was it was red It is a Shooting Chrony, Alpha Model. I bought it from the Smith that built my 6.5 X 284 and used it very little because he not only built the rifle for me he worked up the best load for the max range I wanted to shoot at. Your ramblin again Rusty. Anyway, has anyone used this brand and model and it it any good? Thanks

[Richard]

Yes they are good and yes, I did own one years ago.........actually, my first chronograph was a Chrony. The only thing I will say about the chrony's is that their photo cell spacing is only one foot apart. So, the accuracy of readings will not be as good as a chronograph that has two feet spacings? or for that matter 4' or 8' etc. etc. I have a good friend who use two Oehler ballistic chronographs (over $1,000 ea.) One set just in front of the muzzle and the other at 280 yards. Each has its photo cells/sky screens set exactly 24 feet apart. This allows his results to be accurate within two fps. In order to figure BC's it is imperative that the readings are accurate. The Chrony will definitely get you into the "Ball Park!" However shot to shot readings get more accurate the further apart the screens are. The very short distance between the screens on the Chrony make it difficult for the "start - stop" clocks to accurately pick up the bullet.
Richard

[deadon]

Thank you Sir Is the threaded hole in the bottom of this unit standard size and threads for any cheap camera trypod or do you recommend spending more on something better? Thank again

[Richard]

Yup! Should be a standard 1/4 x 20 thread as used on cameras etc. If you look at that big orange box containing my Pact Chronograph (photos at the Catawba Valley Wildlife Club)? It is just sitting on a cheap light weight tripod!
Richard

[deadon]

Thanks Richard

[boarhog]

IMO, the Shooting Chrony will give you plenty of useful information, assuming it is in good working order. Even if it isn't as scientifically accurate as more expensive models, it should tell you if a particular load is consistent, and how one load compares to another. Far better than not having one!
Boarhog

[deadon]

hello again, the sun screens on this unit are broken. does there have to be two or can I tape one piece that white corigated plastic on all four metal thingys

[Richard]

Deadon...............Most of the time I shoot with mine off! About the only time they will do any good is if the sun is overhead! You plain don't need them most of the time. What will hurt you is if the sun is "glinting" in and hits the photo cell. Even if it comes from an angle. Always make sure the photo cells are shaded. So long as they are unobstructed and can read the bullet passing overhead. What happens is the photo cell picks up the shadow of the bullet against the sky to start and stop the "micro" clocks.
Richard

[deadon]

Thanks again ;D ;D ;D

[minst7877]

Well here goes another question that may seem stupid to some but you never know if you don't ask.

Can you take one of the chronys that hinge open apart and move the sensors out farther?
Or is the brain set to a specific distance and not changeable.

DC

[ET]

Mar 4, 2010 21:13:21 GMT -5 minst7877 said:

Well here goes another question that may seem stupid to some but you never know if you don't ask.

Can you take one of the chronys that hinge open apart and move the sensors out farther?
Or is the brain set to a specific distance and not changeable.

DC

No can do as it's program for calculating velocity has a fixed distance it works on. I believe there is some mention of the Chrony to be fully open for it to properly work to give accurate readings.

Ed

[minst7877]

Thanks ET thats what I suspected but was thinking if you exactly double the distance between the sensors could you multiply the velocity it reads by two and arive at the correct speed?

DC

[ET]

Mar 4, 2010 22:40:02 GMT -5 minst7877 said:

Thanks ET thats what I suspected but was thinking if you exactly double the distance between the sensors could you multiply the velocity it reads by two and arive at the correct speed?

DC

Theoretically it should work if you double the distance of the timer/sensors. How exact doubling the distance has to be I don’t know. But to prove that you would need to know the average velocity of a given load first before trying it with doubling the timer distance.

Out of curiosity how would you approach lengthening the electrical wire for the second sensor?


Ed

[minst7877]

Mine has plugs just like the modular telephone jacks I could just make up a new cord with the jacks.

DC

[ET]

Mar 5, 2010 9:07:03 GMT -5 minst7877 said:

Mine has plugs just like the modular telephone jacks I could just make up a new cord with the jacks.

DC

Thanks for the reponse and enlightenment as my timer cables go under the sensors and can't observe how they are connected.
Now I know.

Ed

[Harley]

I got in on this thread late, but I own the red Alpha Master Chrony; the difference between the Alpha and the Alpha Master is that the Master has a wired remote readout that sits on your bench for easy reading.

The reason I'm mentioning this is that the wiring and the modular plugs look just like any telephone cord, but are in reality a proprietary item; i.e., telephone wire will not work. So, I'm guessing that trying to move the recording sensors apart by adding telephone wire to lengthen the leads won't work, either.

BTW, I totally agree with Boarhog that this model is plenty accurate enough for most cartridge development and B.C. work; I have dozens of times entered into my ballistics program the readings mine generated in order to predict bullet trajectory and it's been close to perfect every time.

Also, for a couple of shooting sessions I was getting abnormally high readings; I finally figured out that I had caught the lip of one half of the housing on my tripod, resulting in a not fully opened box. That's evidence that the Chrony is programmed for a specific sensor to sensor distance.

Harley

[boarhog]

I have an Oehler 35P that uses 3 screens. In the instructions, they stress that the measurement between screens is critical for accurate readings. As little as 1/16-1/8" off will cause the proof channel to show an error. The screens are designed to fit on a piece of 1/2" electrical conduit of 2 to 8 ft long. The outfit comes with a 2' piece. The instructions tell you how to set the DIP switches for 4 or 8 ft spacing, so I made up a 4' piece with the positions for the eyes marked. Since I have no way to test the thing, I can only assume that it is pretty accurate.

Recently, I started having lots of trouble getting it to time shots. It would either flash all dashes on the screen or flash like it does when the proof channel detects a discrepancy. A call to Oehler told me how to individually test the eyes to see if they were working, and I found that the start screen was not starting! In my discussion with Ken O, he said that the cable is a special kind, and that using anything else would introduce "noise" into the unit, and wouldn't work. A replacement "skyscreen" costs about $45.00 plus freight. Since I didn't have anything to lose, and as far as I could tell the wire was just cheap shielded microphone cable with molded 1/4" plugs, I decided to try soldering some good mic cable to the eye. It worked perfectly! In fact, it must have had a bad cable for quite a while. It worked better than ever before! I now know that, if I want, I can extend the cables so that I can set the chrono screens more than 10-15' from the muzzle.