How accurate are your chrono'd velocities?

[guns are dumb]

So today I finally got to go shoot some of my handloads, but I'm trying to figure out if my chronograph (Shooting Chrony F1) is just wacky or what.

Using Vihtavuori N110, I loaded .44 mag with Winchester large pistol primers. I used 18.9 grains of powder under Hornady 240 grain HP-XTP.

Here are the results from my chrono from the first three strings in FPS:

2151
2166
1444 (I suspect this is a true value)
1998
1412 (I suspect this is a true value)

1826
968.7
1415
2151
2134
1082

2212
1385 (I suspect this is a true value)
2149
1206
2204
1149

I'm a very detail oriented person and being my first time reloading I weighed each charge to within .2 grains thrown from an RCBS Uniflow. I also would be able to tell the difference in feel between a 1000 fps load and a 2000 fps load.

Are these velocities trash, is there something wrong with the chrono, why didn't my .357 velocities vary like this?

For reference, reported velocities from .357 (15.4 grains N110, CCI SP magnum, Hornady 125 grain HP-XTP):

1288
1184
1292
1203
1216
1301

1311
1289
1229
1228
1206
1259

Any help would be greatly appreciated.

 

[JCW355]

Did you check those 357 velocities the same day? Those are not kosher, too much variation. Any noticable difference in recoil? Sounds like the chrono is screwy.

 

[Shadowrider]

How close were you to the chrono?

Neither of those look very good but the .44 data just looks whacked.

 

[Blitzfike]

I've found that the angle of the sun to the skyscreens and the distance from the muzzle are big factors in accuracy of my systems. I have two chronys and one pact system. Muzzle blast can skew results quite a bit and having the angle of the light wrong can also give erroneous readings. Another factor is to be sure the battery is fresh. Good luck.. Blitzfike

 

[MoBoost]

You are not shooting inside are you? Florescent lights really mess 'em up.
Outside you got to watch out for moving shadows (like trees).

 

[guns are dumb]

Did you check those 357 velocities the same day? Those are not kosher, too much variation. Any noticable difference in recoil? Sounds like the chrono is screwy.

.357 velocities were taken about 10 minutes prior to the .44, both today.

How close were you to the chrono?

Neither of those look very good but the .44 data just looks whacked.

Chrono was about 12-14 feet away.

I've found that the angle of the sun to the skyscreens and the distance from the muzzle are big factors in accuracy of my systems. I have two chronys and one pact system. Muzzle blast can skew results quite a bit and having the angle of the light wrong can also give erroneous readings. Another factor is to be sure the battery is fresh. Good luck.. Blitzfike

The screens didn't create a shadow whatsoever on the eye, I'm wondering if the angle of the sun was just too low this time of year (shots fired between 1-2:30 today).

It's been a frustrating day for sure.

You are not shooting inside are you? Florescent lights really mess 'em up.
Outside you got to watch out for moving shadows (like trees).

I was at USSA (outside). No trees/shadows whatsoever.



I did find in the user manual where it states high velocity readings can result from too much light or muzzle blast. But at 12-14 feet, I wouldn't think that muzzle blast would be an issue, maybe so with .44 mag?

Also, I'm thinking I might try it again this weekend with it mounted upside down as my tripod has an extendable arm that would allow me to do that, anyone tried that?

 

[JCW355]

I was thinking of lighting and shadows but you amswered that. I'd erase everything and make sure the battery was good and just try again, don't really know on this. Did you try their website for troubleshooting? I don't know their web address but just suggesting it.

 

[grwd]

Unless its a nice overcast day, I dont put too much weight on my chrono.

 

[KurtM]

I put My C.E.D. chrono in a box, painted the inside flat black, and gave it 50 watt D.C. bulbs...it is amazingly consistent, and reads EVERYTHING!! even B.B.s out of the Red Rider. No more shadows...guessing...interpretation! And Mike has access to it! KurtM

 

[Shadowrider]

Unless its a nice overcast day, I dont put too much weight on my chrono.

^^^^^^ This.

I've had far better luck when cloudy than in sun light. And I've tried it in the shade, out of the shade, with screens, without screens, Cocked at 30 degrees, etc., etc. ad nauseum......

When it picks up it's accurate. But when I load up 20 rounds to test and all I can get to pickup is 8.

I think I'm going to have to see your setup Kurt. Got any pics?