Chronograph Tips

[Dougfir]

I'm pretty new to the chronograph. Having one has been fascinating so far, but I also get the sense that little things can have big effects on the readings. I've had the same load give me a 3 shot spread of only 12 or 15 fps, then do the same thing a few days later, but with an average velocity 50 fps faster than before... I'd love to hear any do's and don'ts you have for Chronograph use.
I've been placing mine about 13 or 14 feet in front of the muzzle and trying to center my shots over the device as best I can. I also try to shoot about halfway up the length of the metal rods. I use the sun shades all the time. What else?

 

[TackDriver284]

Did air temp get warmer?

 

[TXbaldhunter]

I ran into this before one morning.What I figured out was,the range I was shooting at the direction was to the east.As the sun rose higher,the angle of light across the eye windows of the chronograph was giving me much different velocities from the previous hour.I moved to another part of the range after that.That shooting direction was to the north.So as the sun rose,the light was crossing the windows the same coming from the side as opposed from the front to the back of the chronograph.I can go back to the range shooting to the north and get very repeatable velocities everytime.

 

[Dougfir]

That's helpful. How about snow? I've heard some people say that snow beneath the device will screw with it. Anyone ever experience that?

 

[Dougfir]

Did air temp get warmer?

No, same (roughly) temp.

 

[hunter24605]

Something that will make setting them up quicker is to use one of those cheapo Bushnell laser bore sighters..I'd put it in the muzzle and hold a piece of paper at the chronograph to see where the laser dot is hitting, and adjust as needed..Much quicker than running back and forth between the chrono and the rifle to adjust it...I also went to lowes and picked up a ceiling light replacement panel to make extenders for the sun-shades. I've made the switch to a MagnetoSpeed and couldn't be happier with it.

 

[Divernhunter]

I set my screens at 4' so I take a small level to be sure they are the same level each time. Not sure just how much difference it makes but one less thing to worry about.

 

[Dr. Vette]

Sunlight will screw you, and cause changes in speed.
I shoot first thing in the morning when the sun is low, or else on cloudy days.

 

[RL338]

As mentioned sunlight will mess with you. The best advise is to keep direct sunlight of the chrono. I received a Magnetospeed Sporter for Christmas and couldn’t be more happier.

 

[Songdog]

When it’s sunny outside.... I put the chronograph in a cardboard box with the sides cut out. You can vary how open the top is to let in more/less light.

Magneto Speed is great.... if all you want is velocity.... you can’t shoot groups with it attached and get viable info.

 

[Nimrod84]

Here's 15 tips / things to look out for - http://precisionrifleblog.com/2012/07/2 ... liability/.

I use the laser bore sighter and piece of paper that Hunter24605 mentioned, it tends to work well as long as the laser doesn't get washed out in bright sunlight.

I'll get about a 50fps spread on the same day from clouds. I like the cardboard box idea that Songdog suggested, but have had issues implementing it as my chronograph mounts on a tripod and the cardboard box tends to catch the wind / muzzle blast and twist & turn everything out of alignment.

Hauling and setup capacity at my ranges prevents me from using a coffin setup.

I'm currently looking into using some discarded plastic fluorescent light covers for sun shields and a light diffuser over the top as shown in the advanced techniques on PRB page. Supposedly they might be rigid enough to hold up to the wind and also handy enough to haul to and assemble at the range. Framing is still my nemesis on a practical application...

 

[ElmerThud]

I use an opaque plastic box resting on the rods over my chrony, the ends cut away so the bullet can pass through. Always seems to work very well when sunny and keeps it all dry should it rain.
It’s also rather more wind resistant, but does have a limit.

You can also just mod an opaque plastic lid to do the same job. I just prefer to use the whole box so light at the sides is diffused.

 

[ShadeTree]

A chrono is going to work best with the most consistent readings all else being equal, on cloudy days. At least the one I use does. My advice for what it's worth would be to try and take readings on cloudy days with the diffuser's removed.

Another trick if you are shooting on a sunny day is to color your bullets with a black magic marker to eliminate (or greatly diminish at least) errors due to reflections and glare off the shiny smooth bullet.

The chrono I use advises to not shoot in the early morning or late evening on a sunny day because the low angle of the sun can also cause reflections off the one side, and an error in velocity. I couldn't tell you either way but I figure the manufacturer should know their product.

I can't speak to a magneto speed but it sounds like many are happy with it.