Chronograph questions

madman25

madman25

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ok do your guys chronies occasionally give odd #s.
testing loads in my rebuilt 700(308 win). using varget and 185,210 bergers, and trying 208 amaxs. right now testing incremental charges. seem to have found charges that have very good vertical grouping at 200 meters. about .7" when kissing the lands, will now oal.

question is every once in a while chrony would report nutter numbers, like i was sending a 208 amax down range at 2830, now as cool as that would be, no way that is happening. going to put a new battery in it next time and see what happens, but though i would as the community.

besides that, really digging the new rig, kreiger 1:10 barrel, straight taper from 1.350 to 1.15 over about 32 inches, ptg one piece bolt, blueprinted/accurized action.

the extra length sure seems to add some speed, getting 208 amax reading, when not crazy of 2670-2690, not bad at all(41.8 varget)
 
Chronographs, two different makes I use will give you the odd reading that's out of line with the rest. I've noticed they are effected by bright sun light, couple that with scattered clouds and may get a lot of false readings.
Cloudy days, heavily overcast are the best for chronies, or block out the direct sunlight.
Bill
 
how far is your chrony from the muzzle
I found best readings at 25 feets or more
closer than that depending on the rifle it can be affected by muzzle blast

if sun is is the way, you can try a picnic table or stic a beech umbrella in the sand on the side
 
had the "shades" they provided on, clear sunny day, about 10-12 in front of barrel, about what the cord to remote display would allow
 
shades are made for indoor use with lights hooked up to them
if the sun is not directly in line over them, they are absolutely useless

one foot off the muzzle, your chrony wont live long
push it down to 15 or 20 feets ( 25 with magnum cartridges) and you will get accurates readings
then, if you want to know what is the exact velocity at the muzzle, you can find out with JBM ballistic calculator
 
my bad on my wording, i meant 10-12 feet in front of muzzle. How high should the bullet pass over the sensors?, i am up 2-3 inches I would estimate. Too close would be very bad.
without buying /making another cable i cant get much further out in front.

its a shooting chrony master beta with remote display,manual says cord is 18 feet, so i guess it would be about 12-15 feet out in front

manual also says to use diffusers on sunny days
 
I think shades are necessary when shooting outdoors, in order to somewhat regulate the ambient light getting to the sensors. I have chronographed loads from a 30-30, outdoors, on the same day, in the same conditions, one after the other, with shades and without, the loads without the shades read approx 200 fps higher than the loads with the shades. I'm pretty sure the reading with the shade is the closest to being correct, because there is no way the loads I was shooting were going at 2500 fps.
 
Riverboy said:
I think shades are necessary when shooting outdoors, in order to somewhat regulate the ambient light getting to the sensors. I have chronographed loads from a 30-30, outdoors, on the same day, in the same conditions, one after the other, with shades and without, the loads without the shades read approx 200 fps higher than the loads with the shades. I'm pretty sure the reading with the shade is the closest to being correct, because there is no way the loads I was shooting were going at 2500 fps.
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I figured something was up when I seen I was pushing 125gr hard cast 9mm bullets at 1800fps thru a PT24/7... At less then a starting load...

Moved the chrony under the shooting shed and and tried with and without the shades... Now I see why some folks build a cardboard box with shutters on the lid for there chronys... They can be touchy.
 
A chrony will be most consistent on an overcast day without the shades.
The shades provide exactly what their name implies for those sunny days.
 
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