I have the CED M2. I am having trouble in several areas. One is getting consistent velocity from the same load from day to day. I was thinking that this might be from not placing the screens the exact same distance from the muzzle each time, or different light conditions on each day. What changes can I expect to see as the day progresses when I start in the shade and by the time I'm done the screens are in the bright sunlight?How much difference in velocity could I expect if I moved the screens 6-12" closer or farther away from the muzzle? I usually set it up about 10' from the muzzle. I had also thought maybe put some sort of shade over the screens all day and use the inferred kit I bought with it, would it help. The other issue I had witch this weekend was when I had switched guns and powered down in between for lunch. When I went back the the first 6 shots read 700fps high, the next 4 and fallowing string dropped back to more normal level albeit about 100fps low. Oh all of the was with a fresh battery by the way anyone have any ideas? TIA Larry.
Cronograph consistancy questions.
- Thread starter Larry M
- Start date
B
B. Harvey
Guest
All but one chrono I have played with has issues with changing light conditions.
The chrono has to see in all light conditions to be able to give you a reading, and the PVM-21 can do it in any light condition including total darkness.
The chrono has to see in all light conditions to be able to give you a reading, and the PVM-21 can do it in any light condition including total darkness.
John Kielly
Shari's fan club
Man, I can just see one gasping its last few breaths in the inky black darkness.........
Larry,
We have very fierce light hereabouts & find it handy to do our chronographing with the skyscreens in shade. If there aren't any trees or other helpful geographic outcroppings, we make do with a beach or golf umbrella or two.
You should be able to find tables to convert instrumental velocoties to muzzle velocities on the internet. I started to look around byt got bogged down in other issues.
John
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I occasionally get some weird velocity 'changes'... sometimes when I'm not using the IR screens, my velocities read surprisingly low. Other times if the angle of the sun is really low to the horizon, I'll get some weird reads.
One thing I was considering to try and 'stabilize' the lighting available to the chrono comes from something I'd read about on a forum oriented towards action pistol and 3-gun matches. From what I gather, there they have to worry about making 'major' or 'minor' power factor, as determined by chrono'ing their loads at the match - and it affects their scoring to boot, so it's an issue of some concern to make sure the chrono reads are consistent from gun to gun, etc.
One of the setups I saw was they basically built a plywood box or 'tube'. The skyscreens were semi-permanently mounted inside (the one I saw actually had two sets, back to back), complete w/ entrance and exit baffles, and lighting internal to the box (can't recall if it was incandescent or fluorescent). Supposedly it worked really well - set the box up on a couple heavy duty tripods, hook up the processing units, and fire through the chronos into a backstop.
Seems like it'd be somewhat easy to fabricate something out of thin ply, or even cardboard & duct tape to do a 'theory-to-practice' and see how it works for our application.
One thing I was considering to try and 'stabilize' the lighting available to the chrono comes from something I'd read about on a forum oriented towards action pistol and 3-gun matches. From what I gather, there they have to worry about making 'major' or 'minor' power factor, as determined by chrono'ing their loads at the match - and it affects their scoring to boot, so it's an issue of some concern to make sure the chrono reads are consistent from gun to gun, etc.
One of the setups I saw was they basically built a plywood box or 'tube'. The skyscreens were semi-permanently mounted inside (the one I saw actually had two sets, back to back), complete w/ entrance and exit baffles, and lighting internal to the box (can't recall if it was incandescent or fluorescent). Supposedly it worked really well - set the box up on a couple heavy duty tripods, hook up the processing units, and fire through the chronos into a backstop.
Seems like it'd be somewhat easy to fabricate something out of thin ply, or even cardboard & duct tape
to do a 'theory-to-practice' and see how it works for our application.
R
Roger rodbolt
Guest
Larry,
The CED M2 allowed me to solve the inconsistency due to sunlight angle, leaves, birds etc. I bought the optional IR screens, then measured my unit while on the tripod. Next trip to the grocery stored I snagged a proper cardboard box, slipped it over the chrono with cutouts in each end to shoot through. Problem solved, consistent reading always.
The CED M2 allowed me to solve the inconsistency due to sunlight angle, leaves, birds etc. I bought the optional IR screens, then measured my unit while on the tripod. Next trip to the grocery stored I snagged a proper cardboard box, slipped it over the chrono with cutouts in each end to shoot through. Problem solved, consistent reading always.