My Chronograph Is Giving Me Fits

[Lead Head]

My chronograph is giving me fits and I hope you or can come up with some good suggestions. Hopefully, suggestions as to how I can eliminate the problems with me present chronograph rather than, "junk it and get a good one." I have a Pact chronograph that is about ten years old. It has the light diffusers but works better without them.
 
One problem is with low readings in the 200 to 250fps range. These I found to be created by the cables attached to the bottom of the sky screens shaking in the wind, so I taped the cables to the mounting bar and that eliminated most, but not all of the low readings generated without firing a shot.
 
The next problem is high readings in the 1200 to 1250fps range. I found these to be caused by muzzle blast. Even when my buddy shoots next to me I get one of the high readings.
 
Both of these problems are not present all the time and I have been unable to identify the conditions or lack of that may be causing the problems.
 
I will be contacting Pact again about these problems. The were not very hellpful the last time I contacted them.
 
Any suggestions will be greatly appreciated.

[BruceP]

You don't say how you set it up but I would think that the high readings from muzzle blast should go away with an increse in distance from the muzzle. The instructions that came with my Oehler says to use at least 13 feet from the muzzle. This is just a guess on the low readings when you don't fire a shot but I would think that you are picking up either insects (Which I have never had happen so that may be off the mark)  or shadows from birds. If it is the latter then the use of the diffusers should help. Since you say it happens less with the wires taped down then you might also have a short.

Bruce

[Lead Head]

BruceP,

I found most of the low readings, 200 to 250 fps were being caused by the wind shaking the cables where they attach to the sensors, most, not all.

I have the start-stop sensors set up 13 to 14 feet from the shooting bench. That is as far as I can set it up and have the brain box beside me on the bench with 15 foot cables.

On another forum, there have been suggestions that the cable solder connection to the sensors could be breaking down and the shaking cables sure indicate this could be true. Other forums tend to indicate the Pact brain box can be sensitive to vibration.

I need to take a few hours and just test all the possibilities. Maybe I will learn where the problem is and how to correct it.

[Land_Owner]

My PACT Model 1XP Chronograph is sensitive to set-up in areas that are over-shadowed (by trees) or in less than direct sunlight.  The sky screens are for consistent detection of the passing projectile by the sensors.  If you "go without", your results may vary. 

Also, the "sweet spot" betwen the sky screens is 2.5" to 6.5" above the sensors.  I painted the leading and trailing edges of my sky screens to attempt to modern gun shoot in the sweet spot.

I've never attempted low velocity (bows) although the Pact is rated between 25 and 5,500 fps.  It is also powered by a 9 volt battery, which could be cause for replacement; comes with a lifetime warranty ; and will not give accurate results when used under fluorescent lights (if your range is lighted).

You didn't say what you were shooting or how your range/chrony is set up, such that a muzzle blast from 15 feet, the manufacturer's recommendation, could affect your readings.  So far, my H&R 357 Handi-rifle, Win 270, AR-15 (223), 243, and lesser calibers have never affected readings from muzzle blast.

[Lead Head]

Chronograph Problems

By the way, I found the low readings I had blained on shaking sensor cables was incorrect. The low readings were caused by rapidly changine sky conditions. The sky was 50-50 blue and small clouds that were moving quite fast, causing problems for the sensors. Today, I manually shook the heck out of the cables and that caused no problems.

The day is June 30th 2010, a bright sun shiny day 75 degrees and perfect for some load testing.

I set up my Pact Model 1 chronograph I had purchased in 1990. I have been having problems with this chronograph picking up readings when my shooting buddy fired his handgun 4ft to my right. I had tried covering the sensor cables, the brain box and whatever else the Pack people had told me to no avail.

True the bad nature of this Pact chronograph, it started off picking up every shot my buddy took. I decided to stand a 2’ x 6’ by 2” thick piece of Styrofoam in front of the two sensors, actually resting against the one nearest me. My buddy continued shooting and I got no more readings caused by his muzzle blast or shock wave.

Obviously, this is no fix to the problem. I even tried cutting the foam down to a height that would allow the use of the chronograph, but the problem came back. My buddy’s shooting caused readings and my own shooting cause readings in the 1225 fps range, which were way too high for the cast bullet load.

I called Pact knowing I had never received a satisfactory answer from them in the past. I described in detail the tests I had conducted today. Pat at Pact suggested turn the sensors 90 degrees to one side and fire in front of them. Also, I could try covering the brain box with something to prevent the shock wave from hitting it. My answer to that was, “You were not listening to me when I described the tests I had done earlier this afternoon. Protecting the sensors from the blast eliminated the problem. It is the sensors that are the problem, not which way the sensors are pointed or where the brain box is, which was behind me.”

Pat had no more suggestions, so I hung up and started considering my options.

Since I have a Pact chronograph purchased with an optional HP printer, both of which are no longer available, buying another manufacturers chronograph would mean both my printer and Pact chronograph are useless junk. There is nothing made today that works with the HP printer I have.

NO. 1 option appears to be – Buy new sensors and hope for the best.

NO. 2 option may be – junk what I have and buy something else, BUT WHAT? Is there a chronograph out there that provides most of the data my Pact does and print it out, that doesn’t have any problems?

I am not at all happy with the people at Pact. They really know little about their product and less about how to fix a problem. I asked if they maintained a file on problems users of their chronograph have had and what was done to fix them? They have no such file. You would think if the sensors have been a problem for many years in the past, perhaps they are still a problem. No suggestion that Pact had worked out a problem of sensors going bad.

Other than buying new sensors hoping that will fix my problem, I AM ALL THROUGH WITH PACT.

Guys, what is one or more of the trouble free chronographs that are on the market now?

[Lloyd Smale]

mine too will give me fits if its overcast or im in the shade. Infered sky screens solved the problem but I dont have power at my range where i use it the most so they dont do much good.  The two chronys i had were even worse. Best cure for me is to just do my chronographing on bright days out in the open. Im retired and can work my scedule around it.

[Ramhunter]

The absolute best chronograph out there is the Oehler 35P.  It has been out of production for several years, but Oehler is making a special limited run this summer to test the market.  It is great, but set your feet, the price will be $575.  Perhaps you could go together with some buddies and buy one, or maybe get your local gun club to buy one for club use.

Details: http://www.oehler-research.com/cgi-local/SoftCart.15.exe/online-store/scstore/p-M35-P.html?L+scstore+qzwn9594ff77ea77+1280588838

[eye shot]

I use the ProChrono and it works great with any gun or bow. If you get the remote unit you can download to your computer then print it out.