Chronograph errors?

[AreWeFree]

I bought a Caldwell chronograph and today was my first time using it. Unfortunately I'm getting bad readings and I'm probably using it wrong.

It's set up on a tripod at least 10 feet away, in overhead sun, with the sunshades on.

I tested two factory loads and got a reading each time, no errors, but the data is bad.

4" barrel, 10 rounds CCI Blazer Brass 124gr 9mm:
1285, 1282, 1281, 1278, 1279, 1276, 1277, 1275, 1284, 1276

4" barrel, 10 rounds Federal HST 147gr 9mm:
1286, 1282, 1271, 1275, 1276, 1278, 1281, 1272, 1271, 1275



Do I need to have the chronograph in direct shade for an accurate reading, or be farther away?

[ExtremeX]

How do you know the data is bad? I guess it seems a little fast?

My Chrony measured 124gr HST out of my 4" XD at about 1161 average.

I did get errors when I first started using mine but it was entirely my fault, the readings were way off, like 400-500 FPS and was user error.

The cause was the how I positioned the chrony in relation to the sun... The shadow the sun shade produced needs to be over the sensors. It also needed to be repositioned as the sun moves the shade off the sensor.

I started using my photography tripod with a ball head as it allows me to lock it in any position quickly at the range. Most of the time it looks really funny because its never level or straight, but it works fine as along as the shadow is over the sensor.

[bsumoba]

they look like good numbers to me. not sure what you are expecting....

[AreWeFree]

I expected about 1,100 fps from the 124gr FMJ, and around 950 fps from the 147gr HP.

Maybe Federal will buy my chronograph so they can post better numbers on their next lab tests.

[AreWeFree]

Thanks ExtremeX, I'll try again with the sensors in shadow.

[Paseclipse]

I was shooting 9mm through a brand new Caldwell chronograph this weekend too. It’s a nice chronograph but I couldn’t get the iPhone app to work and I'm pretty sure it's because my IOS is outdated.

I’d say your numbers look fine since they’re within a decent range. I was testing factory 9mm 115 gr ammunition and got a few readouts from some Tulammo 9mm that read 1,800+ FPS and 4,400 FPS... These numbers are definitely an error since my pistol didn't blow up.

The numbers you see on an ammo manufacturers website isn’t going to match your numbers exactly unless you have the same exact test setup they used.

[Scotty]

My money is on the first sunshade casting a shadow on the 2nd sensor with the muzzle blast. That's what happens to me when I get 1280 fps.

Best way is to put the entire chronograph in the shade, but without having anything over the skyscreens.

[ExtremeX]

My money is on the first sunshade casting a shadow on the 2nd sensor with the muzzle blast. That's what happens to me when I get 1280 fps.

Best way is to put the entire chronograph in the shade, but without having anything over the skyscreens.

muzzle blast really does some weird stuff sometimes...

I had an AR-15 shooter next to me with a brake and my chrony would register a reading / fired shot every time he fired.

[AGunNut2]

Those don't look bad readings usually do, but sure seem crisp for the load
In direct sun yesterday we had some issues with bad readings, but they were all like 500's, or very low. I've never seen your effect, where they look somewhat normal but are off that much.

I think Scotty's nailed it with the shade positioning. We've been using the Caldwells during the winter and had no issues. You should upgrade IOS. I had stability issues until I did. App would crash or not connect. Still crashes sometimes when phone is hot. My buddy's iPad wouldn't connect until he power-cycled it.