tsafa
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Post by tsafa on Nov 30, 2010 15:13:46 GMT
I am looking for any tips I can get for using the Betta Chronograh (blue- self contained).
I am shooting about about 7 feet back to avoid muzzle blast interference. I am still getting some wide deviations in readings.
I already figured out that light is an issue, as the chronogragh started giving error readings as the sun set.
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Post by Larry Jordan on Dec 1, 2010 4:55:11 GMT
How wide are the variations? (What standard deviations are you seeing? In excess of 100fps? ) What are you shooting? Metallic cartridges or muzzleloader? Are you using the supplied diffusers?
Try setting up at 10 to 12 feet and see if that makes a differences. I typically set mine up between 3 and 4 yards from the muzzle. I own an alpha chrony and have used it without any issues for 15+ years. Cartridges chrono'd: 223Rem, 243Win, 260Rem, 6.5x55, 308Win, 44Mag (lever gun). No magnums, however.
Do you have a bow or a blow dart gun? Something you could use to test the chrony in your backyard in good light in the absence of any muzzle blast?
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Post by ShooterMike on Dec 1, 2010 17:24:58 GMT
Good advice from Larry. I always shoot for 15+ feet (about 5 good paces) as I have found smokey loads to interfere with accurate readings. Also, most chronographs are highly dependent on lighting conditions. Direct sunlight onto the electronic eyes (both the start and stop eyes) can have an impact. And not enough light will really give you screwy results. Best time of the day for good results is mid-day when it's cloudy, or a few hours before sundown/after sunrise on sunny days.
But be aware that many loads can be highly variable with velocities. I consider handgun reloads to be excellent if the max spread is 15-20 fps. And with a rifle, 40-50 fps spread is good. If a load that shoots well out of your gun exhibits significantly higher spreads, that still works for me. So long as it is accurate and different distances.
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tsafa
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Posts: 3,309
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Post by tsafa on Dec 4, 2010 4:00:23 GMT
Thanks for the tips. I was shooting from about 7 feet. I will step it back to 15 feet and see if I can get some more consistency. I was shooting .38 spl with 125 grain. 800 f/s was the most common number, but I saw 500's and 1,680 a lot of times too. I even saw 3,200. I will pay more attention to the sunlight. I did not know anything about that at the time I took my readings.
Any advice for shotgun? I know I should use sticks for rail guides so I don't damage the machine. How do I calculate energy for shot, buck, sabot, slug? Should I take the mass of just one shot or all together and throw that into the Energy formula? Thanks.
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Post by Larry Jordan on Dec 4, 2010 15:36:01 GMT
Are you shooting from a bench, bagged position, to guarantee passing through that essential triangle consistently? Even if you are only using slug, no telling where the other ejecta membra will go--they could destroy your chrony.
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tsafa
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Posts: 3,309
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Post by tsafa on Dec 6, 2010 14:44:44 GMT
I think the only way to test the shotgun without risking destroying the chronograph is from very close range. The blast at close range would throw off the reading... so I am guessing testing shotshell is not possible with this machine.
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Post by Larry Jordan on Dec 7, 2010 14:14:23 GMT
Tsafa, I found this in the Chrony User's Manual: [Introduction] Every Shooting Chrony® measures the speed of bullets, arrow, shotgun-pellets, airgun-pellets and paintballs, etc. (Read on.) [Steps on Setup] 6. Chronographs should be at least 10 feet (3 m) from the muzzle of a high-powered rifle, but can be closer to guns with a lesser blast. Five feet (1.5 m) is about right for .22 rimfire firearms. Shotguns should be fired at 5 feet because of the spreading pattern of the shot and errant wads. Arrows must be clear of the bowstring before passing over the first "eye". And from [Stop Before firing that first shot!] D. SHOTGUNS: because flying wads may go in any direction, protect the face of the Chrony by taping a thick piece of clear acrylic over the front of the unit. The acrylic must not extend above the face. Shooting Chrony Inc. offers such protection (see Accessories List). NOTE: When shooting without Diffusers one may substitute soda straws or wooden dowels for the Wire Rods. Hitting the Wire Rods with a bullet could break the Sensor Housings, whereas straws and dowels provide a safer sighting guide. There: Acrylic shield, soda straws...protect you investment.
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tsafa
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Posts: 3,309
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Post by tsafa on Dec 10, 2010 18:14:24 GMT
Thanks much for the help.
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