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I have owned this chronograph for about 6 months and have had very inconsistant results. I can fire my 22 through it and get good readings. If I fire the 44 magnum the results will be good some time and other times give an abnormally low reading. Reduced loads with the 45-70 and the 375 H&H Magnum require that I move the unit out 15 to 20 feet because of muzzel blast. Sometime it records 250 ft/per second other times it will record a beleivable rate.
I finally gave up trying to record a 44 magnum. I called the company, they said make sure the cables don't touch and use a fresh battery . The reviews on the midway web site are generally very good. Mine are very frustrating.
 

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The Hog Whisperer (Administrator)
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I use a chronograph as far away from the bench as the cables will allow. Some people suggest making a 'blast shield' out of a piece of plywood or similar with just a small hole in the middle for bullets to go through.

Revolvers are tough because of the B/C gap and all of the shock waves that get started before the bullet even leaves the barrel. Once with the chronograph too close to the bench, got readings between 1700 and 400 fps for 5 300gr. .45 Colt loads in my Ruger Bisley. They should have been reading around 1200fps.

The same chronograph once picked up velocities from my .35 Rem - when I was maybe 10 feet off to the right! Pretty close to what you would expect the velocities to be too, around 2,000fps with factory 200gr. ammo in a 20 inch barrel. The .35 Rem is not exactly a cannon when it comes to muzzle blast so this just goes to show how sensitive they can be.

Also - do you have any sort of diffuser screens above the sensors? This can help when the sun is not at a good angle for picking up the bullets.

If all else fails, try painting the tips of the bullets a dark color with a magic marker or something similar.
 

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The Troll Whisperer (Moderator)
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I have two chronographs, a Pact PC2 and an Oehler 35P.

With both, the front sensor is always at least 13 - 15 feet away from the muzzle, to lessen muzzle blast effects on the unit.

As stated, muzzle blasts from adjacent benches can affect the Pact chrono - never had the problem with the Oehler. This is somewhat of an anamoly, as the sensors are supposed to be picking up the shadow of the bullet as it passes overhead. Why adjacent muzzle blast will have an effect, I don't know, but have observed a fellow shooter touch off his Swiss K-31 at the table next to me and the Pact would give a 1500 - 1700 fps recording. Stray light can give false readings. I made cardboard shields and painted them black to strap on the diffuser holders of the Pact unit. I've also had strong microwave signals in the area that upset the unit.

If you are shooting loads that have wads beneath the bullets, this could affect the readings.
 

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I also found that I had to move back to 15 feet or so with anything that produced a large muzzle blast (magnum revolvers, big-bore rifles) to get consistant results. I also sometimes have trouble when in direct sunlight with the sun down at an angle. Moving into the shade solved that problem.
If you still have the manual, there's a section that explains how the muzzle blast can interfere with your readings.
 

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Beartooth Regular
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Hi, Swifty:
I have problems with my old Chrony with loads like yours, blunt bullets and low supersonic velocities. Subsonic loads and the .30-06 don't bother it. Using the old Chrony, with it's cardboard diffuser stands means I'm shooting 3-4" over the sensors. Moving out to 20 feet didn't help much.

I found a large cardboard box and cut slots in each end large enough to slide the Chrony is and shoot over the diffuser stands, 9 to 11" over the sensors. I taped white plastic grocery bags over the top of the box for diffusers. The experiment was a success, with a couple of loads recording standard deviations of 10 and 11.

You could try it on an overcast day, with the diffusers off and shooting higher, before making some kind of a high diffuser setup. On the other hand, don't waste your time chronoing black powder loads under a dull overcast. The muzzle flash will get you every time. Then there was the time I got an error signal twice in a row when shooting the flinter. I found a patch sitting on the rear sensor.

I don't have anything with the snort of a .375 H&H, so I won't make any suggestions for it.

Bye
Jack
 
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