Have a Prochrono Chronograph. Used it last year with air rifles and did measure the velocities of 177 and 22 cal pellets sucessfully although it took may trials but the barrel was only a few feet from the chronograph. Took it out today to the shooting range. I could only put the chronograph 5 feet from the 8 mm mauser barrel. Shot 2 shots. One was 175 grain at 2500 fps and the other was 175 grain at 2700 fps. Both just showed zero. Had a fresh battery. It was partially cloudy day but amount of sunshine looked good. Did not use the sunshields. The bench where the chonograph was at did have a roof over it. Can you see anything that I am doing is wrong.? Any tips? What part of the arc defined by the wires should I shoot across. Should I invest in a tripod? Do I have a crappy chronograph and should get another model. Any suggestions of what to buy? Watched a video on using this model and only thing I could see different is he put the unit out 10 feet on a tripod with the sunshades. Thanks in advance for any replies.
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Help with Chronograph
- Thread starter JR924
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BriarPatch99
Senior Member
I would shoot some standard velocity .22 LR over it ....it should read right at 1080 fps ...most chronographs work best at 10' from the muzzle ...
Make sure the Sun is not shining directly into the eyes .... those read the shadow of the bullet passing over to start and stop the clock..... if either one does not read then it is a nothing deal or error... the diffusers are to block direct Sunlight ...use them unless you have a good reason not to...
The Pro is a good chrono unless it has a problem....
Do not get closer than 10' as muzzle blast can cause errors also ....
Make sure the Sun is not shining directly into the eyes .... those read the shadow of the bullet passing over to start and stop the clock..... if either one does not read then it is a nothing deal or error... the diffusers are to block direct Sunlight ...use them unless you have a good reason not to...
The Pro is a good chrono unless it has a problem....
Do not get closer than 10' as muzzle blast can cause errors also ....
chuckdog
Senior Member
At 5' from the muzzle the unit likely didn't detect much more than a blinding flash. No such issues with air guns or arrows.
With most centerfire weapons I setup 5 good steps (about 15 feet) away from the muzzle. See page 6 of your manual.
As Patch posted, I use a Cricket .22lr with standard velocity ammo to confirm my chronographs are working properly. 1050 displayed and I'm ready to shoot.
With most centerfire weapons I setup 5 good steps (about 15 feet) away from the muzzle. See page 6 of your manual.
As Patch posted, I use a Cricket .22lr with standard velocity ammo to confirm my chronographs are working properly. 1050 displayed and I'm ready to shoot.
BriarPatch99
Senior Member
I also paint the whole bullet with a black magic marker to cut down on glint from a shiny bullet ...
The electronic part of the chronic supplies a voltage to the "eye" or photo sensor ....any change of that voltage ....say by a dark bullet passing through the window ....changes the voltage read from that eye ....depending on if it is the "start" eye or the "stop" eye .....if it is the start ...it starts the clock ticking ....the change that happens when the bullet goes over the stop eye ....stops the clock .....this measures the amount of time it takes the bullet to pass from eye to eye ....then the brain converts this time over distance into feet per second velocity ....
Simply a chrono is nothing more than a really fast stop watch with photo sensors ....
The electronic part of the chronic supplies a voltage to the "eye" or photo sensor ....any change of that voltage ....say by a dark bullet passing through the window ....changes the voltage read from that eye ....depending on if it is the "start" eye or the "stop" eye .....if it is the start ...it starts the clock ticking ....the change that happens when the bullet goes over the stop eye ....stops the clock .....this measures the amount of time it takes the bullet to pass from eye to eye ....then the brain converts this time over distance into feet per second velocity ....
Simply a chrono is nothing more than a really fast stop watch with photo sensors ....
trial&error
Senior Member
That flash also throws out a cloud of debris that could confuse the chronograph. Don't use under a roof it uses light to see the bullet, if it's a bright day and diffusers don't occlude the sensor it will not work either.
rosewood
Senior Member
Low pressure rounds work up close, high pressure cartridges need more distance for it to read well. You can shoot shotgun at 2' and it works wonderfully. A high powered rifle or pistol at that distance sometimes I think it reads the smoke, may read only 200 FPS or something ridiculous like that. I move it out and works fine.
As BP said, move it to 10' or further should solve your problem.
Rosewood
As BP said, move it to 10' or further should solve your problem.
Rosewood
RFWobbly
Senior Member
• To clear the muzzle blast it's always good to have the chrono at least 12ft away or you may get numbers like 12,000fps.
• Light is king with chronos. If you are using a camera tripod, then tilt the chrono toward the light. High noon on a highly overcast day is best. Trees can be a huge issue.
• Using chop sticks in place of the metal wires can save your chrono from damage.
• The best "sun screen" is a white lid off one of those Walmart storage boxes, sitting atop the 4 guide-rods
• Light is king with chronos. If you are using a camera tripod, then tilt the chrono toward the light. High noon on a highly overcast day is best. Trees can be a huge issue.
• Using chop sticks in place of the metal wires can save your chrono from damage.
• The best "sun screen" is a white lid off one of those Walmart storage boxes, sitting atop the 4 guide-rods
rosewood
Senior Member
Good ideas I haven't thought of. Thanks!
BriarPatch99
Senior Member
The translucent fiber glass roofing makes an ideal sun screen also ...
Can be cut to fit most any chronograph ... used with wood dowel rods
...
Can be cut wider to help with side glint also ...
Put o rings on dowels to hold in place...
Can be cut to fit most any chronograph ... used with wood dowel rods
...
Can be cut wider to help with side glint also ...
Put o rings on dowels to hold in place...
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