Caldwell Chronograph tweak

[DanK3Pos]

The whole time I've had this chrono I've had really inconsistent readings and more errors than I was content with. So much so that I didn't trust the data.

I re-read the instructions and decided that lighting was probably my issue. The chrono has always been used outdoors and I was contending with clouds, trees blowing in the wind, etc. I did some looking and saw that Caldwell had an LED kit that replaced the stock sun shades. I was able to buy it directly from them for $15 with free shipping (sorry guys, the price has gone back up since then). https://www.caldwellshooting.com/ra...c-precision-chronograph-light-kit/110142.html

When it arrived I cut out a piece of cardboard to fit the perimeter of the LED sun shade (approximately 15"x16") and attached it with zip ties. That allowed me to attach the wiring and battery pack to the cardboard, rather than having it dangling down.

The project was a success. I've sent 100+ rounds over it and am now seeing SDs in the teens and single digits for the first time. I am way, way more confident in my load development efforts now.

I would recommend making the cardboard bigger, as much as +6" on each side. If the sun is anything but directly overhead, the cardboard doesn't really accomplish anything. However, on an overcast day, the LED lights and the cardboard combine to give very accurate readings. Ironically, even though this is the Sunshine State, I've only had the chrono out on one bright day, but it still worked fine.

If there is interest, I can post pictures of my setup.

 

[gifbohane]

I would like to see it.

 

[mmb617]

The problem I had with the stock sun shades is that often the position of the sun in the sky prevents the shades from keeping direct sunlight off the sensors, and direct sunlight screws up the readings if you can get any at all.

I took some scrim cloth which is semi-transparent and allows light through but blocks direct sunlight and attached it in conjunction with the stock shields. I threaded some wire through the slots already in the shields so it extends a few inches beyond them then attached the cloth with velcro so it can be positioned as desired. On the day this pic was taken I was at the range early in the morning and the sun was low in the East so it was shining under the shields. I simply hung my scrim cloth down the side and it worked perfectly.

 

[lordpaxman]

I re-read the instructions and decided that lighting was probably my issue.

I solved my lighting problem a different way: Labradar. Sorry, couldn’t help myself.
When I did have a shoot through chrono, it was a CED and yes you need to have a very consistent illumination of the sensors. Sun in one and sky screen shade in the other does not for a fun time make. I always tried to have a bright day but keep both sensors in the shadow of the clubhouse. Good luck.

 

[cfullgraf]

I added lights to my CED M2 and most of the light issues and faulty triggers of the chronograph went away. I'd recommend getting a light kit for any optical chronograph.

Like lordpaxman, I bought a LabRadar and light issues were a thing of the past. But it has it's own issues that take a little bit of figuring to work out, but lighting is not one of them.

 

[DanK3Pos]

Here is my setup. I used a razor knife to cut out a 16"x15" piece of cardboard, took measurements with my tape measure and calipers, then cut out the openings for the lights. I attached the battery pack to the cardboard with some 3M Double Sided Foam Tape I had from another project. The light kit comes with a battery pack or a wall outlet adapter. In the background you can see my gong at 25 yards I use for handgun chrono testing and load development.

PXL_20201214_150318652

• DanK3Pos
• Dec 16, 2020

Caldwell Chono with LED sun shade.

And here are the results. That is 4.3gr of Unique under an Acme 9mm125gr RN-NLG, mixed range brass, Federal Gold Medal Match Small Magnum Pistol primers (GM200M). Powder was measured on my Chargemaster Lite and loaded semi-single stage on my Dillon 550B. I was working up a load for the Magnum primer, because that is what I have. I attribute the low SD to the scale and the match primers.

Screenshot_20201213-090253

• DanK3Pos
• Dec 16, 2020

Chrono data

 

[DanK3Pos]

I added lights to my CED M2 and most of the light issues and faulty triggers of the chronograph went away. I'd recommend getting a light kit for any optical chronograph.

Like lordpaxman, I bought a LabRadar and light issues were a thing of the past. But it has it's own issues that take a little bit of figuring to work out, but lighting is not one of them.

Santa Claus might bring me a LabRadar, but this was a quick and easy fix for cheap.

 

[gifbohane]

Neat set up..

The Labradar after a short orientation, and $600 out the door, is really really a fine tool. I do not have to wait a half hour for a target change to set up and reposition. Buy either their battery pack or a battery pack, also go to Staples and buy the memory card. I take the chip off of the unit and back to my PC and download the data after every session.

 

[jmorris]

Lots of people get bummed when they wake up to a cloudy, overcast day. I think, is there anything I feel like chronographing?

No screens needed just turn it on and shoot over it, they sky is your screen.