Chronographing load???

a big variation of projectile speeds shouldn't cause an issue at close range if the load is accurate. Although, at distances 150-200fps slower will definitely drop the bullet faster. So if you aren't target shooting over a couple hundred yards, I wouldn't worry about it too much, but keep an eye on it anyhow as they may act differently when the temperature warms up during spring/summer. I've had some powders that were less consistent during winter.
 
With the rounds shooting half inch and the chrony distance only ten feet I'm betting muzzle blast most likely culprit followed by light conditions or a combination of both.

I used to mount the chronograph out in front as far as the cords would reach, about 15 feet...I could have the electronics and readout on the shooting bench for ease of use...
This worked most of the time but I soon figured out when the ambient light was not just right and shooting fast small bullets, I would have erroneous readings until I started setting the screens out 20 feet or more...Since doing this I have never had a problem with velocities that seemed out of whack.

My 22-250's for a while had me dumbfounded as to why they were so flat shooting for the velocity readings the chronograph was giving me...Here was a case where the readings were consistent but erroneously low...Getting the screens out past 20 feet fixed that...readings went from the mid 3500's to the low 3800's exactly where the long range trajectory was telling me the velocity was.

Most times now when I use the chronograph I make sure the thing is set up right by firing a string of 22 long rifle over the screens as I know just what the numbers should. be.
 
Kind of on topic here, but would it be wise to throw up a tarp or something if you were try to get readings on a bright sunny day?
 
titch-- said:
Kind of on topic here, but would it be wise to throw up a tarp or something if you were try to get readings on a bright sunny day?
Click to expand...

I have used a chrony and if you have a sunny day with no clouds you will have a problem if you don't use your screens

sunny day with white clouds no need for screens but you might get the odd error or no reading

the best thing I have found is make a stand and use a large pc of the white plastic sign materinal (looks a bit like cardboard) with the plastic 12-14 inch over screen
big enough or with sides so the sun does not shine directly on sensor
(a roof on posts) fastened down so the wind does not catch it ---- 12 or more feet from the muzzle --- if it has a muzzle break and you have error reading go 15 ft
 
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