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Posted: 4/24/2010 3:20:44 PM EDT
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My chrony arrived this week and I had a change to test it today (it's a Shooting Chrony F1 Master). It seemed to work as expected for .223 / .22, but not for 9mm / .38 / .357. Pistol didn't register often (Err 1) or clocked very low (100's to 300's). Here are examples of the results I got - maybe I'm missing something?
Approx 18' from the bench: .223 - LC07, H335, CCI400, 55 GR Hornady FMJBT W/C - 24 Grains: 2751 fps (avg) - 25 Grains: 2959 fps (avg) 9mm - RWS, SR-4756, Win SP, 124 GR Armscor FMJ - 4.8 Grains: 147.9 fps (avg) Approx 7' from the bench: 9mm - RWS, SR-4756, Win SP, 124 GR Armscor FMJ - 4.8 Grains: 143.6 fps (avg) .38 Special, Win, SR-4756, Win SP, 158 GR SWC - 4.8 Grains: 157.9 fps (avg) - 5.0 Grains: 140.6 fps (avg) .357, Win, SR-4756, Win SP, 158 GR SWC - 5.6 Grains: 389 fps (avg) - 5.8 Grains: 387.2 fps (avg) Federal .22: 1189 fps (avg) As you see, I started about 18' from the bench and then moved it closer to see if I could reduce the number of errors / accuracy with handgun ammo. My handgun loads are pretty light (on purpose)... when I saw the first readings, I wondered about the decimal (the readout doesn't have a decimal showing, but I inserted one since the directions indicate that anything less than 1000 fps reads to the tenth). Taking one reading from .38 special as an example - the read out was 1651. If I don't insert a decimal, it is truly too high for what I was shooting (same with all pistol). If I insert a decimal (165.1), it's too low. My backstop was 50 yards away (paper target). Since it was doing the same thing at 18' as it was at 7', muzzle blast doesn't seem to be the issue. Although I wasn't shooting for accuracy (focused on not shooting the chrony), all of the 9mm / .38 / .357 were hitting paper. Everything I did with rifle (both .223 at 18' and .22 at about 7') seemed about right. I also noticed that I would get "Err 1" or "Err 9" when shooters 2 - 3 benches down were firing. It doesn't seem to be an issue with the diffusers - again, rifle worked fine... In both positions, I tried shooting through the lower third, middle third and upper third beneath the diffusers - didn't seem to matter. Ideas? Rick |
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My old green Chrony (1989/1990 vintage) came with cardboard windows... I took and improved on the windows, they is rasied slightly, made from 2 layers of corrugated cardbaord (Dominos box), with plastic glued to them (plastic license plate with dealer name)..
Because I use mine with AR-15 (high sight post above bore), I marked off alignment lines to insure straight consistent shots through the windows, when all the lines align and top of sight post on the sight line, fire a shot. I thnk you are still too close at 7'..... even with pistol, I use the "sight" line for height, align all the lines, fire. NOTE -> the flyer bullet holes is from fellow ARFCOM people I let use my Chrony... 
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I agree that 7 feet is probably too close.
What where the conditions while you where shooting? Sunny, cloudy etc...? On a day with bright white clouds in the air I sometimes have problems if I use the sunscreen. Days like that I set it up without them. You need light to get good readings with a chrono. |
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You might also have to adjust the height the bullet passes over the chrono. Too low or too high makes for errors. I have a Beta Master and I use tape on soda straws to sight through as you want the bullet to be between 4" and 6" above the screens. I sight on the top tape line, midway between the straws and that ensures that the bullets are going over the screens at he proper height, even if I'm using one of my ARs. BTW, I use soda straws because if you hit the straw it doesn't break the plastic housing as will happen with the steel rods. Also, I made up a duplicate set that I keep in the box in case I hit a straw, however, in the two years I've had it I haven't hit them . . . . . . yet.  |
| I shoot all my test loads at 10'. Seems to work fine for me. Are you using a "new" battery or one that's been laying around for some time? After shooting one load and gathering the data, try turning the unit off and then back on before you start another test load. I know you shouldn't have to but it may help. Which of course would mean it's probably the machine and needs to be fixed. Good luck. |
| Yep - new battery in it, and I was cycling the power on and off between groups. I guess what frustrates me is that it works fine for the rifle rounds (which to me means it functions right and I had it set up right), but not for the pistol at two different distances. |
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